exam 3 - actual notes hi

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Cell signaling

purpose is to coordinate cell activities and responses

Stages of cell signaling

reception transduction response

Reception stage

ligand binds receptor

Transduction stage

signal converted into cascade of steps

Response stage

cell changes activity or gene expression

Local signaling

affects nearby cells

Endocrine signaling

hormones travel through bloodstream

Ligand

signal molecule that binds receptor

Receptor

protein that detects signal and initiates response

GPCR

receptor that activates G protein using GTP

RTK

receptor that dimerizes and autophosphorylates

Ligand gated ion channel

receptor that opens channel when activated

Intracellular receptor

binds signals that cross membrane like steroids

Phosphorylation

adds phosphate to activate protein

Protein kinase

enzyme that phosphorylates proteins

Dephosphorylation

removes phosphate to deactivate protein

Protein phosphatase

enzyme that removes phosphate groups

cAMP

second messenger made from ATP

Adenylyl cyclase

enzyme that produces cAMP

Calcium ions

second messenger released from ER

IP3

opens calcium channels in ER

Signal amplification

one signal activates many molecules

Scaffolding proteins

organize signaling pathways

Apoptosis

programmed cell death

Caspases

enzymes that carry out apoptosis

Cell cycle

purpose is growth repair and reproduction

Interphase

cell grows and replicates DNA

G1 phase

cell growth

S phase

DNA replication

G2 phase

prep for division

M phase

mitosis and cytokinesis

Mitosis

division producing identical cells

Cytokinesis

division of cytoplasm

Cleavage furrow

animal cell cytokinesis

Cell plate

plant cell cytokinesis

Mitotic spindle

moves chromosomes during division

Centrosome

organizes spindle fibers

Kinetochore

attachment site for spindle fibers

Cyclins

proteins that regulate cell cycle

CDKs

enzymes activated by cyclins

MPF

complex that triggers mitosis

Checkpoints

G1 G2 M control progression

Cancer

uncontrolled cell division

Benign tumor

localized growth

Malignant tumor

cancer that spreads

Metastasis

spread of cancer cells

Chromosomes

structures containing DNA

Chromatin

uncondensed DNA

Sister chromatids

identical copies of chromosome

Centromere

region holding chromatids together

Diploid

2n two sets of chromosomes

Haploid

n one set of chromosomes

Gametes

sex cells sperm and egg

Zygote

fertilized egg

Homologous chromosomes

pair with same genes from parents

Allele

different version of gene

Locus

location of gene

Meiosis

produces haploid gametes

Meiosis I

separates homologous chromosomes

Meiosis II

separates sister chromatids

Crossing over

exchange of DNA in prophase I

Independent assortment

random alignment in metaphase I

Random fertilization

any sperm can fertilize any egg

Genetic variation

sources are crossing over independent assortment fertilization

Mitosis vs meiosis

mitosis identical meiosis diverse

Mendel studied

inheritance using pea plants

True breeding

produces same traits each generation

Hybrid

offspring of different traits

Genotype

genetic makeup

Phenotype

observable traits

Homozygous

two same alleles

Heterozygous

two different alleles

Dominant allele

expressed over recessive

Recessive allele

only expressed if no dominant

Law of segregation

alleles separate in gametes

Law of independent assortment

genes assort independently

Punnett square

predicts genetic outcomes

Multiplication rule

probability of independent events multiply

Addition rule

probability of either event add

Incomplete dominance

blended phenotype

Codominance

both alleles expressed

Multiple alleles

more than two forms of gene

Pleiotropy

one gene affects many traits

Epistasis

one gene affects another

Polygenic inheritance

many genes control one trait

Chromosome theory

genes located on chromosomes

Thomas Hunt Morgan

showed genes on chromosomes using fruit flies

Sex chromosomes

X and Y determine sex

SRY gene

triggers male development

X linked traits

more common in males

Y linked traits

passed father to son

X inactivation

one X turned off in females

Linked genes

inherited together on same chromosome

Recombination frequency

used to map gene distance

Nondisjunction

chromosomes fail to separate

Aneuploidy

abnormal chromosome number

Polyploidy

extra chromosome sets

Deletion

loss of chromosome segment

Duplication

repeat of segment

Inversion

segment reversed