CH 1 Flashcards by Taylor Walker

3 reasons why cells divide

reproduction:
- -asexual reproduction (mitosis)
- -produce gametes for sexual reproduction
growth and development (meiosis)
- -from fertilized egg to multicelled organism by mitotic divisions
repair and renewal
- -replace cells that die from normal wear &tear or from injury

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What is the cell cycle?

Cycle of cell growth, replication of the genetic material, and nuclear and cytoplasmic division

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What are the three stages of interphase?

G1 (gap 1)
S (synthesis)
G2 (gap 2)

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What are the two stages of cell division (meiotic or mitotic)

M (mitosis)

C (cytokinesis)

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term for nuclear division

karyokinesis

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term for cytoplasmic division

cytokinesis

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Stages of Interphase and Mitosis

Interphase: G1, S, G2
Mitosis: Prophase, Metaphase, Anaphase, Telophase, Cytokinesis

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What is a cell that is arrested in the G^0 phase?

What is an example?

a cell that is differentiated and won’t divide

i.e. Neurological cells

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What are the two fundamental processes that occur w/ the cell cycle?

Chromosomes and DNA REPLICATE

Chromosomes & DNA SEPARATE

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At what two stages is the cell primarily regulated?

DNA replication

Cell division

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At what two points in Interphase are cells checked?

G1 and G2

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What a chromosome divides, ________ are formed. This is made of two “parts,” each containing the full genetic code.

sister chromatids

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After a cell replicated during the S phase, the chromosome is made of two sister chromatids connected at the ________.

centromere

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these genes tell cells to divide
if you remove this gene, you get cancer
gene that once causes cancer once mutated but is necessary for proper cell cycle control

protooncogene

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gene that tells cells to divide

Ex. p53

tumor suppressor gene

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What are the three major controllers of the cell cycle?

protein kinases
- -regulatory subunit: cyclin
- -catalytic subunit: Cdk
phosphatases
ubiquitin-protein ligases

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master controller of cell cycle
contains regulatory subunit (cyclin) and catalytic subunit (Cdk)
phosphorylate inhibiting or stimulating controls
heterodimeric–containing a dimer of 2 different groups

protein kinases

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master controller of cell cycle
cleaves phosphates (i.e. CD25)

phosphatase

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master controller of cell cycle

responsible for proteolysis

ubiquitin-protein-ligases

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process that destroys cell protein

proteolysis

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subunit of protein kinase
recognizes target of protein kinase
is degraded during cell cycle

cyclin

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subunit of protein kinase
phosphorylates inhibiting or stimulating proteins
contains catalytic site for 6 ATP of energy
not functional without cyclin–turns off
protooncogene

Cdk

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involved in cell cycle control

marks protein for degredation

ubiquitin protein

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adheres target of ubiquitin protein to the target

ubiquitin ligase

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Cyclin-Cdk complex: G1

Cyclin D | CDK4, CDK5

Cyclin-Cdk complex: G1/S-CDK

Cyclin E | CDK2

Cyclin-CDK complex: S-CDK

cyclin A | CDK2, 1

Cyclin-Cdk complex: M-CDK

cyclin B | Cdk1

Cdk needed at G1 stage of interphase When Cyclin D is complexed with Cdk4 or 6, it is a functional protein kinase and is needed to pass through this stage of interphase

G1 Cdk | --cyclin D, CDK4, CDK6

Cyclin-Cdk needed at checkpoint b/w G1 and S

G1/S Cdk - -cyclin E - -Cdk2

what causes the rapid decline of cyclin during the cell cycle?

ubiquitin attaches and proteolysis occurs

a Cyclin-CDK complex, Cyclin B/Cdk1

MPF: "maturation promoting factor" or mitotic promoting factor

what causes the rapid increase in cyclin at certain stages of the cell cycle?

the presence of cyclin rapidly increases when a specific gene is turned on

What are the 4 ways in which CDK is regulated?

1. Association with cyclins 2. Activating phosphorylation of threonine around position 160 3. Inhibitory phosphorylation of threonine 14 and 15 4. Association with Cdk Inhibitors (CDKIs)

what are 4 examples of tumor suppressor genes?

CKI CAK WEEI Cdc25

How does CKI inhibit CDK activity in the cell cycle?

CKIs physically block activation or substrate/ATP access | CKIs can also stop formation--last step in cell cycle inhibition

How does association with cyclins regulate Cdk activity in the cell cycle?

through cyclin synthesis and destruction (proteolysis) Cdk is always present but is not activated unless attached to proper cyclin --the gene that encoded that specific cyclin must have been expressed

How does activating phosphorylation of thronine around position 160 regulate Cdk activity in teh cell cycle?

through CAK: Cdk Activating Kinases | --the CDK must be phosphorylated by CAK to active it and be capable of phosphorylating the targets

How does inhibitory phosphorylation of threonine 14 and tyrosine 15 regulate CDK activity in the cell?

1. Wee1 Kinase--inhibitory phosphorylation 2. Cdc25 phosphatase--remoces inhibitory phosphate - -If time is not proper, Thr14 and Tyr15 can be phosphorylated for inhibition and it is not an active - -If time is proper, inhibitory phosphates must be removed with a phosphatase (i.e. Cdc25) to activate cyclin/Cdk complex

common phosphatase that removes inhibitory phosphates to activate Cyclin/Cdk complex

Cdc25

tumor suppressor gene | kinase that inhibits phosphorylation

WEE1

the cell-cycle control system depends on ______

cyclical proteolysis

destroys target during proteolysis

protoron

what are two ubiquitin ligases? (cause destruction of cyclins and other cell-cycle regulators)

1. Skp, Cullin, F-Box containing complex (SCF) | 2. Anaphase-promoting complex (APC)

Ubiquitin ligase ubiquitylation and destruction of G1/S-cyclins and CKI proteins that control S-phase initiation causes destruction of cyclins and other cell-cycle regulators

Skp, Cullin, F-Box, containing complex (SFC)

ubiquitin ligase destruction of cyclins and other cell cycle regulators responsible for ubiquitylation and proteolysis of M-cyclins and other regulators of mitosis

Anaphase-promoting complex (APC)

what four things influence the G1-S checkpoint?

Growth factors....gene expression! nutrients cell size DNA damage

What three things regulate the G1-S checkpoint?

protein phosphorylation protein degradation inhibitory proteins (CKIs)

What three things influence the G2-M transition state?

cell size DNA damage DNA replication

What influences the Spindle Assembly Checkpoint?

chromosome attachments to spindle

major controller of getting through G1/S checkpoint prevents passage of cell cycle tumor supressor binds transcription factor E2F, inhibiting it from transcribing gene (i.e. products needed for synthesis) When this is phosphorylated, it releases E2F

retinoblastoma protein

what are the 5 steps in the passage through the G1 phase to the G1-S checkpoint?

1. Growth factors induce synthesis of D cyclins 2. D-cyclins activate Cdks 4,5,&6 3. Phosphorylation of Rb releases E2F 4. E2F transcription factor regulates expression of specific genes 5. Synthesis of proteins required for entry into S phase

what are the 4 steps of the passage through the S stage G1-S checkpoint?

1. Growth inhibitory factors induce synthesis of CKIs 2. Phosphorylation of CKI triggers its degradation by SCF & proteosome (proteolysis of CKI) 2. S-phase CDKs are activated by the release of CKIs 3. Phosphorylation of replication complex triggers DNA synthesis

What is phosphorylated at the G2-M checkpoint?

Histones Microtubules Lamins

What are the 4 stages of the G2-M Checkpoint?

1. Completion of DNA synthesis releases replication complex 2. Activation of a phosphatase (CDC25) 3. CDC25 phosphatase activates MPF (Cyclin B/CDK1 complex) 4. Mitotic cyclins trigger: - -chromosome condensation - -assembly of the mitotic spindle - -breakdown of nuclear envelope

what regulates chromosomes attaching to the spindle?

tension - -If proper tension is present, chromosomes move - -If not proper tension, chromosomes reorient

What can occur if improper tension occurs?

unequal # of chromosomes segregating to the poles

mitotic arrest deficient 2 prevents activation of APC until proper orientation

Mod2

ubiquitin promoting ligase that triggers breakdown of sister chromatids this attaches ubiquitin to securin and proteolysis of Cyclin B CDK1

APC (anaphase-promoting complex)

protein that holds two sister chromatids together

Cohesin

place on centromere where spindle microtubules attach

kinetochore

anaphase inhibitor that inhibits separase | keeps cohesin from being degraded so sister chromatids stay together

SECURIN

enzyme that breaks down cohesin | inhibited by securin (anaphase inhibitor)

SEPARASE (separin)

transcription factor that controls expression of certain genes a mutation of this causes 70% of cancer

p53

cell division that provides cells for growth, cell replacement, and asexual reproduction maintains chromosome number -- conservative

mitosis

type of cell division that produces cells for sexual reproduction reduces chromosome number by 1/2 -- nonconservative

meiosis

why are chromosomes not visible during interphase?

b/c they need to be accessible / thinly spread

why are chromosomes compacted during mitosis?

to reduce separation problems

what are the major parts of the chromosome during metaphase?

2 sister chromatids held together by COHESIN applied during S phase connected at the CENTROMERE

unreplicated chromosome | one DNA molecule, one chromosome

monad

replicated chromosome composed of two chromatids two DNA molecules (one per sister chromatid) one chromosome

dyad

number of complete SETS of chromosomes in a cell

ploidy

two sets of chromosomes (Human = 46) present in somatic cells (2n)

diploid

half of the usual number of chromosomes found in the somatic cells of a species i.e. number of chromosomes in a germ cell (Human = 23) present in germ cells (n)

haploid

amount of DNA in haploid genome of a given species expressed in picograms or megabase pairs "quantity of DNA"

C value

1 pg = ______ MB

965 MB

1 MB = ________ nucleotide base pairs

10^6

complete set (n) of chromosomes inherited as a unit from one parent

genome

pair of chromosomes carrying same genetic information | Ex: ABO locus - Chromosome 9

homologous chromosomes | "homologs"

location of a gene on a chromosome

locus

the kinetochores of chromosomes connected at their centromeres are oriented _____ on the metaphase plate

bilaterally | i.e. toward different poles

what allows sister chromatids to separate?

the breakdown of cohesin by separase

hold chromatids together during metaphase, inhibiting progression into anaphase degraded by separin (separase)

cohesins

securin degradation is promoted by ______

APC-dependent polyubiquitination

T/F: ploidy does not change at any point during mitosis?

CH 1 Flashcards

(85 cards)