Cell Bio Exam #5 Vocab

actin filament

a cytoskeletal filament made up of actin dimers structured together such that they leave clefts for ATP/ADP binding

actin-binding protein

a protein that binds to actin filaments to change their behavior

centriole

a structure found within the centrosome matrix

centrosome

a major microtubule organizing center found near the nucleus in non-mitotic cells

cilium

a microtubule-based structure that beats back and forth

cytoskeleton

a protein-based intracellular network that provides motility, structure, and other functions for cells

dynamic instability

referring to the microtubule tendency to grow and shrink repeatedly and independently of one another

dynein

a motor protein affiliated with microtubules that moves toward the ^^negative^^ end of the fibril; associated with the axoneme

intermediate filaments

strong, ropelike cytoskeletal structures that provide cells with mechanical strength

kinesin

a motor protein affiliated with microtubules that moves toward the ==positive== end of the fibrill

linker proteins

transmembrane proteins that connect cytoskeletal components across the nuclear envelope to the nuclear lamina

microfilaments

the actin-based fibers that make up actin filaments

microtubule

intracellular rod-like structures made up of tubulin that extend from organizing centers

microtubule-associated proteins

proteins that are affiliated with microtubules, stabilizing them and preventing their disassembly

motor proteins

enzymatic proteins that perform ATP hydrolysis to move

myofibril

a rodlike organelle found in muscle cells

myosin

a motor protein associated with actin filaments that moves toward the ==positive== end of the fibril

nuclear lamin

a structural component of animal cell nuclei made up of intermediate filaments

nuclear lamina

a fibrous network beneath the inner nuclear membrane made up of nuclear lamins that provides mechanical support to the nuclear envelope

nuclear envelope

the double membrane surrounding the nucleus

sarcomere

the contractile unit of a myofibril

tubulin

the protein dimer that makes up microtubules

anaphase

the stage of mitosis where sister chromatids are pulled to opposite ends of the cell at their kinetochores by the mitotic spindle

anaphase-promoting complex (APC/C)

a large enzyme complex that ubiquitylates cyclin and securin to regulate the concentration of the former and to promote anaphase

apoptosis

programmed cell death

aster

a mitotic centrosome-microtubule complex that emerges during prophase

Cdc25

an activating phosphatase whose dephosphorylation of M-Cdks enhances their activity

Cdk (cyclin-dependent kinase)

a kinase enzyme that is only functional when bound to cyclin

Cdk inhibitor protein

a protein that prevents Cdk from proper function

cell cycle

the process by which cells grow and divide

cell cycle control system

a series of intracellular signaling pathways that regulate entry into the various stages of the cell cycle

chromosome condensation

the formation of chromatin into highly condensed chromosomes

cohesin

a protein that stabilizes the association of sister chromatids

condensin

a protein that promotes the condensation of chromatin

contractile ring

an actin-based ring that pinches the plasma membrane into two daughter cells during cytokinesis

cyclin

a regulatory protein that activates Cdks and directs them to their target molecules

cytokinesis

the formation of two daughter cells after mitosis via the contractile ring’s constricting and pinching off of the plasma membrane

G1 phase

the stage of interphase characterized by high metabolic activity and preparation for DNA replication

G2 phase

the stage of interphase characterized by a fully grown cell, replicated DNA, and final preparations for mitosis

interphase

the portion of the cell cycle wherein cells spend the majority of their lifespans

kinetochore

a protein complex to which the microtubules of the mitotic spindle bind, regulating entry into anaphase

M phase

the stage of the cell cycle where mitosis is performed

metaphase

the stage of mitosis where sister chromatids line up along the spindle equator

mitogen

an extracellular signaling molecule that stimulates the transition into the S phase

mitosis

the process by which a cell divides to produce two genetically identical daughter cells

mitotic spindle

a microtubule-based structure that moves chromatids during mitosis

p21

a Cdk inhibitor protein that is activated by the transcription of p53

p27

a Cdk inhibitor protein that hinders Cdk activity by sterically blocking cyclin from binding during G1

p53

a protein that is activated in response to damaged DNA during the G1 phase, activating p21 to suppress Cdk activity

prometaphase

the stage of mitosis where the breakdown of the nuclear envelope occurs and the mitotic spindle attaches to the kinetochores of sister chromatids

prophase

the stage of mitosis where the mitotic spindle begins to form

retinoblastoma (Rb)

a regulatory protein that binds to transcription regulators to prevent them from activating genes that promote cell proliferation

S phase

the stage of interphase characterized by DNA replication

sister chromatid

a collection of tightly-wound DNA that has been replicated to be divided between two cells during mitosis

securin

a protein that inhibits separase in its active conformation

separase

an enzyme that catalyzes the degradation of cohesins to promote anaphase

spindle pole

the centrosome complex at either end of the cell toward which sister chromatids are pulled during anaphase

telophase

the stage of mitosis where two new nuclear envelopes begin to reform around the separated chromatids

Wee1

an inhibitory protein kinase whose phosphorylation of M-Cdk hinders its activity

allele

a variant of a gene

asexual reproduction

reproduction that does not involve the fusion of gametes

bivalent

a pair of duplicated paternal and maternal chromosomes

chiasma

a junction at which crossing-over occurs

crossing-over

a process occurring during prophase I of meiosis involving the exchange of DNA sequences in the bivalent

diploid

a cell that has *2n* number of chromosomes

fertilization

the process by which two gametes come together to produce a diploid zygote

gain-of-function mutation

a typically dominant alteration in a gene that enhances the function of its corresponding protein

gamete

a haploid germline cell produced in meiosis

genotype

the actual genetic code that determines a certain feature or characteristic in an organism

germ line

the family of cells involved in reproduction

haploid

a cell that has *n* number of chromosomes

heterozygous

having two different alleles of a gene

homolog

a chromatid that has a corresponding chromatid from the opposite parent

homologous recombination

the repairing of a double-stranded break in DNA by using the replicated strand as a template

homozygous

having the same two alleles of a gene

law of independent assortment

homologous chromosomes that encode for different traits assort themselves independently of one another

law of segregation

each parent produces a gamete containing one allele for a certain trait

loss-of-function mutation

a typically recessive alteration in a gene that deactivates the function of its corresponding protein

meiosis

the process of reductive division to produce gametes

pairing

the grouping of duplicated homologs together during prophase I of meiosis

pedigree

a chart resembling a family tree that predicts the phenotype of a couple's offspring

phenotype

the resultant protein or other characteristic emerging from the expression of a gene

sexual reproduction

reproduction involving the fusing of gametes in fertilization to yield a zygote

somatic cell

any cell that is not involved in reproduction

zygote

the diploid product of fertilization

apical

referring to the apex of a structure

basal

referring to the base of a structure

basal lamina

a barrier that separates and protects the epithelium from connective tissue

benign tumor

a mass of excessively proliferating cells that remain in a single cluster

cancer

unregulated cell division and cell growth

cell wall

a network of pectin, cellulose, and other fibers that provides strength and protection to plant cells

cellulose fibril

a bundle of cellulose molecules that provide strength to plant cell walls

collagen

a protein-based fiber that organizes into bundles and provides tensile strength to animal cells

connective tissue

collections of cells within animals that consist largely of extracellular matrix

differentiated cell

a cell that has a specialized function

embryonic stem cell (ES)

a stem cell that comes from an embryo and can differentiate into any type of cell in the organism

epithelium

a single layer of cells that forms the outer surface of a tissue

extracellular matrix

a network of proteins and other molecules that surround, support, and give structure to cells and tissues

genetic instability

referring to a highly variable number of chromosomes and high rate of mutation characteristic of cancer cells

induced pluripotent stem cells (iPS)

a stem cell that is reverted to an embryonic state through the artificial expression of transcription regulators