uwec bio 221 exam 4 (cell signaling, cell cycle, mitosis, meiosis, mendelian genetics)

Environmental conditions for why cells need to communicate

communication helps cells respond to change conditions(temp, PH, nutrition availability)

cell to cell comunication

essential for coordinating activities inn multicellular organisms (nerve cells transmitting singles)

themes in cell communication

cell membrane receptors, signaling molecules, signal transduction pathways, cellular responses

cell membrane receptors

detect external signals and relay information inside the cell

signaling molecules

act as messengers

signal transduction pathways

convert signals into cellular responses via a series of molecular events

cellular responses (cell communication)

responses include gene expression, enzyme activation, or changes in cell behavior

direct intercellular signaling

connexons/innexons, plasmodesmata

connexons/innexons

form channels between animal cells

plasmodesmata

connect plant cells

contact dependent signaling

signal molecules remain attached to the cell membrane; receptor binds upon contact

autocrine signaling

self-signaling

paracrine signaling

local signaling or nearby cells

endocrine signaling

long-distance signaling via bloodstream

stages of cell signaling

receptor activation, signal transduction pathway, cellular responses

receptor activation

signal binds to extracellular domain, altering receptors cytoplasmic domain

signal transduction pathway

cascade of events transmitting signals to intracellular targets

cellular responses (cell signaling)

altering gene expression, protein activity, or metabolic pathways

cell surface receptors

enzyme linked receptors, ligand-gated ions channels, g protein-coupled receptors

Enzyme-linked receptors

Binding of ligand activates catalytic domain of the receptor

ligand-gated ion channels

ligand binding opens/closes the channel for ion passage

G protein-coupled receptors

signal activates g-protein to relay messages inside the cell

intracellular receptors location and domains

located in cytoplasm/nucleus with ligand-binding, dna-binding, and transcription-activating domains

intracellular receptors mechanisms

signaling molecule crosses the membrane and activates receptor, influencing gene expression

signal transduction pathway activation

activation via enzyme-linked receptor, ras g-protein activation, signal transmission, transcription factors

activation via enzyme-linked receptor

kinase domain activates via phosphorylation using atp

ras g-protein activation

signal receptor triggers ras by converting gdp to gtp

signal transmission

signal propagates through kinase cascade, eventually activating transcription factors

transcription factors

proteins that regulate gene expression, leading to cellular changes

second messengers

small molecules that relay messages inside the cell. commonly used in signal transduction pathways

cAMP production

atp converted to cAMP by adenylate cyclase; cAMP is degraded to AMP by phosphodiestrase

role of cAMP

functions as a second messenger in signaling pathways

cAMP in signal transduction

epinephrine activate GPCR, leading to cAMP production. cAMP activates PKA, which regulates cellular responses

epinephrine and muscle cell response

PKA regulates enzymes like glycogen phosphorylase and glycogen synthase, adjusting glycogen metabolism

signal amplification

a single signal molecule can activate multiple molecules, leading to a rapid and amplified response

cell theory

all living organisms are made of cells. the cell is the basic unit of life. all cells come from preexisting cells

stages of cell growth

g1, s, g2, mitosis, cytokinesis

G1 phase

cell grows, performs normal functions, and prepares for DNA replication

S phase (stages of cell growth)

DNA replication occurs; chromosomes become two sister chromatids

G2 phase

cell continues to grow, organelles replicate, and the cell prepares for mitosis

mitosis

division of the nucleus into two identical nuclei

cytokinesis

division of the cytoplasm, forming two separate cells

g1 checkpoint

checks for DNA damage and sufficient recourses

g2 checkpoint

verifies DNA replication accuracy

m checkpoint

ensures chromosomes are properly attached to spindle fibers

autosomes

non-sex chromosomes (22 pairs)

sex chromosomes

determines biological sex(x and Y)

diploid

2 sets of chromosomes

haploid

1 set of chromosomes

interphase stages

G1, G1 restriction, G0 phase, S phase, G2, checkpoints

G1

growth and prep for DNA replication

G1 restriction

checkpoint to determine if cell division could occur (based on size, contact, and chromosome integrity)

G0 phase

cell exits cycle; can re-enter if conditions improve

S phase (interphase)

DNA replicates, forming sister chromatids (DNA content doubles but not chromosomes number)

G2

preparation for mitosis, organelles replicate

checkpoints

verifies readiness to proceed; errors lead to repair or apoptosis

cyclin-dependent kinases

enzymes activated by cyclins to regulate cell cycle (phosphorylation of proteins and differential gene expression)

cyclins

A group of proteins whose function is to regulate the progression of a cell through the cell cycle and whose concentrations rise and fall throughout the cell cycle

Cyclin-CDK complexes

Must both be activated and inactivated for cell cycle to progress.

role of cyclin E-Cdk complex in transitioning from G1 to S phase

phosphorylates retinoblastoma (Rb) protein, releasing E2F transcription factors to promote S phase

role of growth factors in transitioning from G1 to S phase

trigger production of cyclin e, initiating progression

role of p53 in G1

activates dna repair or induces apoptosis if damage is detected

M phase checkpoint

ensures all chromosomes are properly aligned before anaphase

APC (anaphase promoting complex)

triggers separation of sister chromatids

stages of mitosis

prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis

prophase

chromosomes condense and spindle fibers form

prometaphase

nuclear envelope breaks down and spindle fibers attach to kinetochores

metaphase

chromosomes align at metaphase plate

anaphase

sister chromatids separate and move to poles

telophase

nuclear envelope reforms and chromosomes decondense

cytokinesis in animals and plants

animals: cleavage furrow forms

plants: cell plate forms

astral microtubules

anchor spindle poles to cell membrane

kinetochore microtubules

attach to chromosomes at the kinetochore

polar microtubules

push the poles of the cell away from each other during anaphase

Anaphase A

chromatids move to poles (kinetochore microtubules)

anaphase B

spindle elongates, separating poles (polar and astral)

mitosis result and type of cells

two identical diploid cells; somatic cells

meiosis occurs in

germ cells

meiosis results

four haploid, genetically unique gametes

genetic recombination

crossing over and independent assortment increase diversity

deletion

loss of a segment

duplication

extra copy of a segment

inversion

reversal of a segment

translocation

segment moved to another chromosome

Euploid

normal number of chromosomes

Aneuploid

Abnormal number of chromosomes.

triploid

3 sets of chromosomes

tetraploid

four sets of chromosomes

what must happen before mitosis can occur

DNA replication during the S phase of interphase. this ensures that each chromosome consists of two sister chromatids

how does the chromosome number at the beginning of mitosis compare to the number in G1

the numbers remain the same but each chromosome consists of two sister chromatids after DNA replication

how does the DNA at the beginning of mitosis compare to the DNA content in G1

it double during s phase

centriole def and function

cylindrical structures that help organize microtubules during cell division

when do centrioles replicate and why is this necessary for mitosis

centrioles replicate during the s phase of interphase to ensure each daughter cell receives a complete centrosome for organizing the spindle apparatus

major events of prophase in mitosis

chromosomes condense, nuclear envelope begins to break down, spindle apparatus starts to form

major events of prometaphase in mitosis

nuclear envelope dissolves, microtubules attach to chromosomes at kinetochores, chromosomes begin to move toward the metaphase plate

do microtubules from both plates attach to each chromosome

yes, microtubules from opposite poles attach to the kinetochores of each sister chromatid

major events of metaphase in mitosis

chromosomes align at metaphase plate, spindle fibers ensure proper attachment for separation

what moves the chromosomes to align at the metaphase plate

tension created by spindle microtubules pulling from opposite sides

major events of anaphase in mitosis

sister chromatids separate and move to opposite poles, microtubules pull chromatids apart, poles move further apart

chromosome during anaphase

sister chromatids separate and become individual chromosomes