Study
Review All
Quiz!
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Blending model of inheritance |
all traits of parents are blended in their offspring. ex. red flower + white flower = pink flower |
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What are the problems with the blending inheritance model? |
a. all individuals in a population should eventually look alike b. some traits seem to skip a generation & appear in the next, unblended |
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Gregor Mendel |
Austrian monk; the "father" of modern genetics |
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Particulate Model of Inheritance |
parents pass distinct particles (alleles) to their offspring that do not blend with other particles |
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Diploid |
two copies of every chromosome |
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Homologous chromosomes |
a pair of chromosomes, one copy from each parent |
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Haploid |
one copy of every chromosome. half the number you need |
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gametes |
name for the haploid eggs & sperm |
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Why are gametes haploid? |
They have to be haploid or chromosome number would double every generation |
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Gene |
piece of DNA that codes for a protein |
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Alleles |
different forms of the same gene |
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Phenotype |
physical description of organism ex. tall, short, brown, black |
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Genotype |
describes which alleles are present ex. AA, Aa, aa or BB, Bb, bb |
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Homozygous |
Two copies of the same allele |
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Heterozygous |
two different alleles |
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Dominant |
one allele masks, hides or blocks the appearnce of another allele |
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Recessive |
the name for the allele that is hidden by the dominant allele |
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Incomplete dominance |
phenotype of heterozygote is intermediate between phenotype of two homozygous genotypes |
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Co-dominance |
phenotype of heterozygote simultaneously shows both phenotypes |
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Multiple Alleles |
two or more alleles for a gene |
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Epistasis |
one gene affects the phenotypic expression of another gene |
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Pleiotropy |
one gene with multiple effects on the phenotype. |
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Polygenic trait |
one phenotypic trait is controlled by many genes ex. skin color & height |
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How can you tell if a trait is polygenic? |
The phenotypes of a polygenic trait form a normal distribution (bell-shaped curve) |
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Principle of segregation of alleles |
sexually reproducing, diploid individuals have two copies for each gene and these alleles separate from each other such that each egg or sperm gets only one allele |
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Principle of independent assortment |
alleles of one gene assort independently of the alleles at another gene |
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Autosomes |
chromosomes not involved in sex determination |
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sex-chromosomes |
chromosomes that are invovled in sex determination *equal # of male & female chromosomes, equal ratio of XX and XY* |
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sex-linked traits |
genes found on sex chromosomes and show sex-specific patterns of inheritance |
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X-Chromosome Inactivation |
one of a females two X chromosomes shuts down early in development, leaving one functional copy, just like in males |
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Barr bodies |
the name for the chromosome that is inactivated |
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How does a calico cat get its mosaic coat color? |
Coat color is x-linked. different cells in the body shut down different x chromosomes, different x chromosomes produce different patches of color |
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What is the central dogma? |
a flow of genetic information DNA>RNA>protein |
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DNA is transcribed into what? |
mRNA molecule |
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Where does transcription occur? |
nucleus |
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Does transcription occur on both strands of the DNA molecule? |
no, one strand at a time |
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Does transcription require a primer? |
no |
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What enzyme joins the RNA nucleotides together? |
RNA Polymerase |
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Where does the mRNA molecule go after transcription? |
cytoplasm |
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Where in the cell does translation occur? |
Cytoplasm |
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WHat is the actual site of translation? |
ribosome |
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What is a ribosome made from? |
RNA; it is a 2 part sub-unit of RNA |
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What is a codon? |
triplet of bases in the mRNA |
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What is tRNA? |
transfer RNA |
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what does tRNA do? |
trasports amino acids to the ribosome |
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What is an amino acid? |
1 of 20 different molecules used to make a protein |
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What is an anticodon? |
the tRNA complement to the mRNA codon |
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What is a gene? |
piece of DNA that codes for a protein that has a start and a stop codon |
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What does gene expression mean? |
DNA went through transcription and translation |
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What is a promoter? |
DNA in front of the gene where regulatory proteins bond |
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Does one gene always make one complete protein? |
no |
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DNA Structure |
a. DNA is a linear molecule |
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What are the three main parts of the nucleotide chain? |
a. phosphate group |
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DNA characteristics |
1. deoxyribose sugar |
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RNA characteristics |
1. ribose sugar |
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What type of molecular bond holds the two nucleotide chains of DNA together? |
Hydrogen bonds |
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DNA replication |
DNA packed tightly into visible chromosomes only during cell division |
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Strand separation |
DNA strands are unzipped by enzyme helicose |
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Complementary base pairing |
A,G,C,T bases find their complements |
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Polymerization |
enzyme DNA polymerase attaches new bases and re-zips new strands |
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What is needed to start adding new bases to the nucleotide chain? |
RNA primer: short piece of RNA that allows DNA polymerase to begin adding new bases |
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Mutations |
rare; beneficial mutations are rare; only one in a billion nucleotides mutates. Most mutations are bad or have very little effect |
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What are the five most common types of DNA mutations? |
1. point mutations: TTAGT>ATAGT |
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what are restriction enzymes? |
enzymes derived from bacteria that cut DNA specific sequences where the sequence is the same on both strands of DNA |
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What are the two main types of Eukaryotic cell division and what are their functions? |
mitosis: to make more body cells |
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MITOSIS Interphase |
a. cell growth |
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What are sister chromatids? |
chromosome plus an identical copy stuck to it |
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What is a centromere? |
protein tie that holds sister chromatids together |
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What is a centriole? |
cell organelle that organizes microtubules |
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Microtubules |
protein filament that moves things inside the cell |
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What is the metaphase plate? |
imaginary line the middle of the cell where the chromosomes line up |
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what are karyotypes? |
visual picture of condensed chromosomes |
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Kinetochore microtubules attach __________ to _________ and __________ chromosomes apart |
centriole; centromere; pull |
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what separates during anaphase of mitosis? |
sister chromatids |
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___________ attach centriole to centriole and __________ the cell apart. |
Polar microtubules; push |
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Cytokinesis |
another name for cell division |
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How do animal cells divide? |
use a contractile ring |
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What is the contractile ring made from? |
actin |
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What is different about cytokinesis in plant cells? |
plants don't have genes to make actin protein, so plants build a cell wall in the middle and two halves continue to grow |
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What are the final products of mitosis? |
2 genetically identical diploid daughter cells |
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What happens during Meiosis 1? |
identical to mitosis except at anaphase, homologus chromosomes separate. |
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What happens during Meiosis 2? |
1 cell division, no DNA replication; where sister chromatids separate |
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Is there DNA replication during Meiosis 2? |
NO |
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What separates during Meiosis 2? |
sister chromatids |
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How many daughter cells are produced at the end of meiosis 2? |
four |
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Are the daughter cells produced at the end of Meiosis 2 haploid or diploid? |
haploid |
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In human males, how many of the four cells become sperm cells? |
four |
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In human females, how many of the four cells become egg cells? |
one |
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What do the terms "crossing-over" and recombination refer to? |
refers to the chromosomes exchanging arms; mixing and matching of chromosomes no two eggs/sperm produced will ever be the same |
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Why is recombination important? |
to generate lots of genetic variation |
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when does recombination occur? |
prophase of meiosis |
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What does radiation do to chromosomes? |
breaks chromosomes |
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What is the genetic bases of Down syndrome? |
trisomy 21 -->3 copies of chromosome 21 |
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Asexual reproduction |
reproduction without sex. DNA comes from one individual |
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Binary fission |
cell splits into two identical cells. clones. bacteria and some protists |
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Budding |
genetically identical individuals grow off of other individuals |
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Fragmentation |
pieces break off and grow into completely new individuals |
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parthenogenesis |
production of offspring from unfertilized eggs |
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Advantages of asexual reproduction |
don't have to spend time looking for a mate |
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Disadvantage of asexual reproduction |
very little genetic variation among offspring |
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Sexual reproduction |
meiosis and sex. DNA comes from two different individuals |
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Silmultaneous Hermaphrodite |
has male and female reproductive organ. do not usually self-fertilize |
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Why don't hermaphrodites self fertilize? |
no genetic variation |
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Sequential Hermaphrodite |
individual born as one sex, but changes to the other |
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Protandry |
born a male, change to a female |
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Protogyny |
born a female, change to a male |
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Pseudohermaphroditism |
a mismatch between chromosomal sex and either internal sex organs, external sex organs or psyche (sex identity) |
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Advantages of sexual reproduction |
adds independent assortment, segregation of alleles and recombination in addtion to mutation which creates lots of genetic variation |
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Disadvantages of sexual reproduction |
have to go find a mate |
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Genetic Gender determination |
chromosomes determine gender of offspring |
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SRY gene |
Y-linked gene in mammals that blocks female genes on the x chromosome. Allows male-ness to develop |
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Triple X (XXX) |
fertile females develop normally. most never know they have an extra X. X chromosome inactivation shuts off extra X too |
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Klinefelter's Syndrome (XXY) |
phenotypically male. normal except sterlie. x-linked recessive traits often not expressed |
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XYY Syndrome |
males with no real phenotype differences. may be a little taller than they would otherwise |
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Androgen insensitivity syndrome |
genetically male (XY), phenotyically female. have internal testes rather than ovaries |
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Haplodiploidy |
males are haploid & females are diploid |
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Environmental Gender Determination |
the environment determines the sex of the offspring |
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Temperature Gender Determination |
crocodiles, some turtles, some fish. males develop at one temperature and females develop at another |
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Environmental Toxins |
PCBs and other pesticides can "feminize" turtles and gulls |
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Social Environment |
some fish and frogs can change sex if males or females are rare |
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Fertilization |
fusion of egg and sperm |
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External fertilization |
occurs outside the females body |
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Broadcast spawning |
releasing millions of gamete into the water and hope that they find each other |
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Internal fertilization |
occurs inside the female's body 1. sperm penetrates the egg |
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Acrosome |
sac of enzymes that allows the sperm to digest its way to the egg cell membrane |
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fertiliazation membrane |
membrane that prevents a second sperm from the entering egg |
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fraternal twins |
2 or more different eggs are fertilized at the same time |
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identical twins |
one fertilized egg splits into two genetically identical eggs |
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Three ways to handle a fertilized egg |
1. Ovipary |
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Ovipary |
eggs laid outside of the body |
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Ovovivipary |
eggs are kept inside the body until hatching |
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Vivipary |
young develop inside the female and receive constant nourishment via a placenta |
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**Placental mammal ask about this one |
developing embryo is connected to females body by a placenta |
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Marsupial |
young nourished outside female's body inside a marsupium (pouch) |
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Where are sperm produced? |
The testes |
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At puberty, the _____, releases ______ in pulses every 1-2 hours. This causes the anterior pituitary to increase the production of _____ and ______. |
Hypothalamus, GnRH, LH, FSH |
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Luteinizing hormone (LH) |
causes testes to secrete testosterone |
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Follicle-stimulating hormone (FSH) |
causes testes to start sperm production |
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What do FSH and testosterone regulate? |
sperm production |
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What affect do anabolic steriods have on sperm production? |
excess testosterone causes GnRH, LH, & FSH to decrease. Testes stop producting sperm and shrink |
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What is the main function of the scrotum? |
keep the testes at the best temperature for sperm production |
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What temperature is best for sperm production? |
In humans, slightly below body temp is best. Testes can move up & down to regulate temperature |
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How much fluid per ejaculate? |
about a teaspoon or two |
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how many sperm per ejaculate? |
100-300 million |
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How fast is an ejaculation? |
25-30 mph |
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How fast can sperm swim? **ask about this one** |
90 seconds |
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How long can sperm survive in the vagina? |
a couple of days at best |
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How long can sperm survive outside the vagina? |
a couple of minutes |
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Oxytocin |
produced in males too. found in semen. may help males form bonds with females. "Trust hormone" |
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Prolactin |
pituitary hormone released in males & females after orgasm. creates feelings of relaxation and satisfaction |
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Can a male control the sex of his children? |
only in the laboratory. XY sperm are lighter than XX . sperm can be separated by weight |
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Bulbourethral glands |
-produce alkaline fluid to reduce acidity in urethra & vagina |
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Prostate Gland |
--produces alkaline fluid to reduce acidity in urethra & vagina. And activate sperm swimming |
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seminal vesicles |
--produce the sugar fructose to feed swimming sperm |
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Prostaglandins |
stimulate contractions of female reproductive tract |
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Why do you we need the prostaglandins? |
Help move sperm farther up reporductive tract to where the egg is waiting |
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Where are eggs produced? |
Ovaries |
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how many eggs does an ovary contain? |
--At birth around 1 million |
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how many eggs released in a lifetime? |
about 400-500 |
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What causes the cramps associated with the menstrual flow? |
Contractions of uterine muscles to expel the endometrail cells and unfertilized egg. |
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How does the "pill" work? |
--Fools the body into thinking it is pregnant. |
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What is the relationship between body fat and menstruation? |
females shold have at least 17% body fat in order to menstruate regularly |
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menopause |
after about age 50, few egg follicales remian, ovaries become inactive and estrogen levels fall |
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Fertiltiy drugs |
usually consist of large amounts of FSH, causing release of multiple eggs |
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Where does fertilization occur? |
Fallopian tube |
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how long is the egg in the fallopian tube? |
12-24 hours |
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when are women most fertile? |
between days 10 and 20 of menstrual cycle. (middle of their cycle) |
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How many pregnancies end in miscarriage? |
1 in 6 |
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Endometrium |
lining ofthe uterus where fertilized eegg will implant |
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Endomtetriosis |
5-10% of women. Endometrail cells grow in places other than the uterus. usually painful |
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Ectopic pregnancy |
fertilized egg implants somewhere other than the uterus |
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HCG (Human Chorionic Gonadotropin) |
--hormone produced by cells around implanted embryo. |
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What is a pregnancy test? |
a quick test to see if HCG is present in the urine. if so, you are pregnant |
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Apoptosis |
--programmed cell death |
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Normal control of cell division |
1. one cell sends a signaling molecule to another cell |
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MPF |
mitosis-promoting factor. |
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Cyclins |
concentration increases to a threshold & starts mitosis |
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proto-oncogenes |
genes involved in starting mitosis. also called growth factors |
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tumor suppressor genes |
genes that stop cell division. can also trigger the expression of proteins that kill the cell |
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BRCA1 & BRCA2 |
some mutations in these genes significantly increase the risk of getting breast cancer |
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How do cells lose control of cell division? |
mutations in the genes that control cell division (mutagens/carcinogens) |
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Cancer |
uncontrolled cell division that can spread to toher cells & tissues |
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The study of cancer is called? |
oncology |
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3 characteristics of cancer |
1. cells divide & grow abnormally |
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Metastasis |
when cancer cells move & infect other parts of the body |
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Tumor (Neoplasm) |
abnormal growth of tissue. does not have to be cancerous |
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Benign |
relatively harmless tumors that do not spread to other tissues ex. warts & moles |
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uterine fibroids |
non-cancerous tumors in the uterus. |
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malignant |
agressive cancers that rapidly spread to other cells & tissues |
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What percent of americans will develop some form of cancer during their lifetime? |
40% |
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Lymphoma |
a type of cancer that originates in white blood cells (lymphocytes) |
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Leukemia |
cancer of the blood cells (red or white) or bone marrow |
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basal cell carcinoma |
slow growing & most common type of skin cancer |
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malignant melanoma |
an agressive cancer of melanocytes (skin pigment cells) |
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lung cancer |
very common cancer among men and women. smoking is the leading cause. about 20% lung cancer cases are related to second-hand smoke |
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prostate cancer |
men only; nearly all men will develop this if they live long enough. After age 45, regular checkups are a good idea |
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breast cancer |
--most common cancer among women. |
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can men get breast cancer? |
yes but 100 times less common in men |
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some factors that might increase the risk of breast cancer |
a. genetics |
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some factors that might reduce risk of breast cancer |
a. lower age @ first childbirth (<25) |
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Mastectomy |
removal of 1 or both breasts |
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Oophorectomy |
removal of the ovaries |
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Hysterectomy |
removal of all or part of the uterus |
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cancer treatments |
a. immune system |
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CANCER TREATMENT Immune system |
some white blood cells attack cancer cells |
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CANCER TREATMENT Radiation |
breaks chromosomes so good against cancer cells, bad for healthy cells. |
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CANCER TREATMENT Chemotherapy |
a wide range of drugs that find & destroy cancer cells or destroy supporting tissue (capillaries) |
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What is development? |
the process by which a fertilized egg increase in size and complexity & becomes a reproductive adult |
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Ectoderm |
--outer surface of a fertilized egg |
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Endoderm |
lining of digestive tract; also liver, pancreas & lungs |
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Mesoderm |
muslces, skeleton, gonads, kidneys, most of the circulatory system |
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what are pleuripotent (embryonic) stem cells? |
cells that retain the ability to become all different cell types. |
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What do the neural crest cells do? |
they will move to the head and form teeth, nerves, facial bones, skin pigment cells |
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Does embryo growth occur by mitosis or meiosis? |
mitosis |
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Aging (senescence) |
a progessive decline in cell & organ function over time, leading to organism death |
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Evolutionary Theory of Aging |
aging occurs because of the accumulation of mutations w/ late-life effects. natural selection can't eliminate them |
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Why can't natural selection eliminate mutations? |
These mutations have their effects only after reproduction has occured. |
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What is the contractile ring made from? |
Actin filaments |
