Cellular level of organization

Cell biology

study of cellular structure

Cell biology

study of cellular structure

plasma membrane

cell membrane that encloses a cell and controls the traffic of molecules in and our of a cell

transcription

making RNA from DNA

translation

making protein from RNA

mitosis

nuclear division in which a cell divides once and produces two genetically identical daughter cells

cells

basic living, structural, and functional units of the body composed of characteristic parts, the coordinated function of which allows each cell type to fulfill a unique biochemical or structural role

Cell structure and function are

intimately related

3 principle parts of a cell

plasma membrane, cytoplasm, nucleus

plasma membrane

separates inside of cell from outside

cytoplasm

all cellular content between plasma membrane and nucleus

nucleus

large organelle that houses the cell's DNA

2 components of cytoplasm

cytosol and organelles

cytosol

clear, gelatinous colloid in which organelles are embedded

organelles

structures w/in a cell that have specific functions, where metabolism occurs, where things are stored

plasma membrane

surrounds and contains the cytoplasm, flexible barrier

plasma membrane makeup

50% lipid 50% protein

protein channels

gatekeepers, anything that isn't polar can't pass through, very selective about what comes in and out

lipid bilayer

basic framework of the plasma membrane

3 types of lipids

phospholipids, cholesterol, glycolipids

phospholipids

lipid w/ phospate attached

cholesterol

steroid with attached hydroxyl group

glycolipids

lipid w/ carbohyrate attached

extracellular

outside of cell

are amphipathic molecules

lipid bilayer

lipid bilayer arrangement

have both polar charged parts and nonpolar uncharged parts w/ the polar head pointing out and the nonpolar tail facing toward the center of the membrane

cholesterol molecules in the lipid bilayer

are weakly amphiphotic and are interspersed among other lipids

where glycolipids appear in the membrane layer

the part that faces the extracellular fluid

phospholipid bilayer

2 parallel layers of molecules(amphiphillic)

integral membrane proteins

are firmly embedded and extend into or across the entire lipid bilayer

peripheral membrane proteins

are more loosely associated with membrane, can be at inner or outer layer, and can be stripped away from the membrane w/out disturbing membrane integrity

integral membrane protein functions

ion channels, transporters, receptors, enzymes, linkers, cell identity markers

peripheral membrane protein functions

help support plasma membrane, anchor integral proteins, and participate in mechanical activities of cells

microvilli

extensions of plasma membrane that serve to increase cell's surface area

where is the brushboarder of the microvilli located

on the apical cell surface

cilia

hair-like projections of a cell that move using a powerstroke

functions of cilia

sensory(inner ear, retina), line respiratory and uterine tubes, some move mucus along surface layer

flagella

whip-like structure, much longer than cilia(sperm cell)

membranes

are fluid structures, rather like cooking oil, because most of the membrane lipids and membrane proteins easily move in the bilayer

cholesterol in the membrane

serves to stabilize the membrane and reduce membrane fluidity

are selectively permeable

plasma membranes

is permeable to small, nonpolar, uncharged molecules, but impermeable to ions and charged or polar molecules, is also permeable to water

lipid bilayer portion of the plasma membrane

transmembrane proteins

act as channels or transporters and increase the permeability of the membrane to molecules that cannot cross the lipid bilayer

how macromolecules, unable to pass through the plasma membrane get through to the cytoplasm

vesicular transport

membrane potential

an electrical gradient occurring because the inner surface of the membrane is more negatively charged and the outer surface is more positively charged

maintaining the concentration and electrical gradients are

important to the life of the cell

electrochemical gradient

combined concentration and electrical gradients

mediated transport

moves materials w/ the help of a transporter protein

nonmediated transport

does not use a transporter protein

active transport

uses ATP to drive substances against their concentration gradients

passive transport

moves substances down their concentration gradient w/ only their kinetic energy

vesicular transport

moves materials across membranes in small vesicles, either by exocytosis or endocytosis

exocytosis

process in which a vesicle in the cytoplasm of a cell fuses w/ the plasma membrane and releases its contents from the cell, used in the elimination of cellular wastes and in the release of gland products and neurotransmitters

endocytosis

process in which a cell forms vesicles from its plasma membrane and takes in large particles, molecules, or droplets of extracellular fluid

nonpolar, hydrophobic molecules move freely through the

lipid bilayer

diffusion through the lipid bilayer

is important for life processes such as nutrients, waste, and gas exchange

integral transmembrane proteins

allow passage of small inorganic ions too hydrophillic to pass through lipid portion of bilayer

passage through the integral transmembrane proteins

is generally slower than diffusion across the lipid portion w/ less opportunity

osmosis

movement of water from an area of higher concentration to an area of lower concentration

hydrostatic pressure

force of pressure against membrane that opposes osmosis from forcing water back toward higher concentration of water

osmotic pressure

pressure of a solution proportional to concentration gradient of solute particles on side of membrane w/ more solutes

tonicity

measure of a solution's ability to change the volume of cells by altering their water concentration

in an isotonic solution

red blood cells maintain their normal shape

in a hypotonic solution

red blood cells undergo hemolysis(explode)

in a hypertonic solution

red blood cells undergo crenation(shrink)

most prevalent primary active transport mechanism

sodium ion/potassium ion pump

requires 40% of cellular ATP, all cells have 1000's of them, maintains low concentration of K+ and high concentration of Na- in the cytosol

sodium ion, potassium pump

secondary active transport

energy stored in the form of a sodium or hydrogen ion concentration gradient is used to drive other substances against their own concentration gradients

bringing something into a cell

endocytosis

releasing something from a cell

exocytosis

phagocytosis

cell eating by macrophages and WBCs, particle binds to receptor proteing and whole bacteria or viruss are engulfed and later digested

pinocytosis

cell drinking, no receptor proteins

cytosol

the intracellular fluid, is the semifluid portion of cytoplasm that contains inclusions and dissolved solutes

composed mostly of water, plus proteins, carbs, lipids, and inorganic substances

cytosol

are either in a solution or in a colloidal(suspended) form

chemicals in cytosol

the medium in which many metabolic reactions occur

cytosol

specialized structures that have characteristic shapes and perform specific functions in cellular growth, maintenance, and reproduction

organelles

network of protein filaments throughout the cytosol

cytoskeleton

functions of cytoskeleton

cell support and shape, organization of chemical reactions, cell and organelle movement

some epithelial cells have______ projecting from surface

cilia

contain microtubules

cilia

some epithelial cells have_____ on surface to increase surface area for absorption

microvilli

tiny spheres consisting of ribosomal RNA and several ribosomal proteins

ribosomes

function of ribosomes

protein synthesis

ribosomes are made in the_____ and assembled in the_______.

nucleolus, cytoplasm

made up of a network of membranes

endoplasmic reticulum

studded w/ ribosomes

rough E.R.

does not contain ribosomes on its membrane surface

smooth E.R.

functions of ER

transports, synthesizes, packages, and stores proteins, also detoxifies chemicals, and releases calcium ions involved in muscle contraction

processes, sorts, and delivers proteins and lipids to the plasma membrane, lysosomes, and secretory vesicles

Golgi Complex

membrane-enclosed vesicles that contain powerful digestive enzymes and have and internal pH that reaches 5.0,

Lysosomes

functions include digesting substances and recycling organelles

lysosomes

is bound by a double membrane

mitochondria

the outer membrane is smooth; the inner membrane is arranged in folds called cristae

mitochondria

site of ATP production in the cell by the catabolism of nutrient molecules

mitochondria

self-replicate using their own DNA

mitochondria

has circular DNA w/ 37 genes

mitochondria

usually the most prominent feature of a cell

nucleus

these cells don't have a nucleus

red blood cells

these muscle fibers have several nucleus

skeletal muscle fibers

parts of the nucleus

nuclear envelope, nuclear pores, nucleoli, DNA

located w/in the nucleus, cell's hereditary units, are arranged in single file along chromosomes

genes

# of human DNA molecules or chromosomes

46

non-dividing cells contain nuclear_____, which are loosely packed DNA

chromatin

dividing cells contain_______, which are tightly packed DNA that copied itself before condensing

chromosomes

long molecule of DNA that is coiled together w/ several proteins

chromosomes

have 46 chromosomes arranged in 23 pairs

human somatic cells

various levels of DNA packing represented by

nucleosomes, chromatin, fibers, loops, chromatids, and chromosomes

determine the physical and chemical characteristics of cells

proteins

where the instructions for protein synthesis are found

in DNA, in cell's nucleus

involves transcription and translation

protein synthesis

process by which genetic information encoded in DNA is copied onto a strand of RNA called messenger RNA(mRNA), which directs protein synthesis

transcription

process of reading the mRNA nucleotide sequence to determine the amino acid sequence of the protein

translation

process by which cells reproduce themselves

cell division

cell division that results in an increase in body cells and involves a nuclear division called mitosis, plus cytokinesis

somatic cell division

cell division that results in the production of sperm and eggs and consists of a nuclear division called meisosis, plus cytokinesis

reproductive cell division

an orderly sequence of events by which a cell duplicates its contents and divides in two; consists of interphase and the mitotic phase

cell cycle

contain 46 chromosomes or 23 pairs of chromosomes

human somatic cells

two chromosomes that make up a chromosome pair

homologous chromosome or homologs

cell w/ a full set of chromosomes

diploid cell

a cell w/ only one chromosome from each pair

haploid

during this stage of the cell cycle, the cell carries on every life process except cell division

interphase

the doubling of DNA and centrosome occur in this stage

interphase

phases of interphase

G1, S, G2

what happens in G1

cytoplasmic increase

what happens in S phase

replication of chromosomes

what happens in G2 phase

cytoplasmic growth

doubling of genetic material happens during this part of interphase

S phase

the distribution of tow sets of chromosomes, one set into each of two separate nuclei

mitosis

stages of mitosis

prophase, metaphase, anaphase, telophase

during this phase of mitosis, the chromatin condenses and shortens into chromosomes

prophase

during this phase of mitosis, the centromeres line up at the exact center of the mitotic plate or equatorial plane region

metaphase

this phase of mitosis is characterized by the splitting and separation of centromeres and the movement of the two sister chromatids of each pair toward opposite poles of the cell

anaphase

this phase of mitosis begins as soon as chromatid movement stops; the identical sets of chromosomes at opposite poles of the cell uncoil and revert to their threadlike chromatin form, microtubules disappear or change form, a new nuclear envelope forms, new nucleoli appear, and the new mitotic spindle eventually breaks

telophase

the division of a parent cell's cytoplasm and organelles;

cytokinesis

this process begins in late anaphase or early telophase w/ the formation of a cleavage furrow

cytokinesis

what happens after cytokinesis is complete

interphase begins

uncontrolled cell division

cancer

3 possible destinies of a cell

remain alive and functioning w/out dividing, to grow and divide, or to die

induces cell division

Maturation promoting factor(MPF)

cell death, is triggered from outside the cell or from inside the cell due to a "cell-suicide" gene

apoptosis

pathological cell death due to injury

necrosis

results in the production of haploid cells that contain only 23 chromosomes

meiosis

Four phases of meiosis 1

prophase1, metaphase1, anaphase1, telophase1

during this phase of meisosis1, the chromosomes become arranged in homologous pairs through a process called synapsis

prophase1

during this phase of meiosis1, the homologous pairs of chromosomes line up along the metaphase plate of the cell, w/ the homologous chromosomes side by side

metaphase1

during this phase of meiosis1, the members of each homologous pair separate, w/ one member of each pair moving to an opposite pole of the cell

anaphase1

in meiosis2, the phases are similar to those in mitosis, but result in ______

four haploid cells