Molecular Biology - Ch 19

Front 1

M Phase

Back 1

Mitosis & Cytokinesis

Front 2

Sister Chromatids

Back 2

Two attached chromosomes

Front 3

The cell spends most of its life in . . .

Back 3

. . . Interphase

Front 4

S Phase

Back 4

Synthesis phase - Phase during which new nuclear DNA is Synthesized

Front 5

G1 Phase

Back 5

Gap Phase between M & S Phase during which a cell grows

Front 6

G2 Phase

Back 6

Gap Phase between S & M Phase during which a cell grows

Front 7

Mitotic Index

Back 7

Percentage of cells undergoing mitosis at any given time

Front 8

G0 phase

Back 8

Phase in which arrested cells await a signal to re-enter the cell cycle

Front 9

Terminal Differentiation

Back 9

A state in which a cell has left the cell cycle, never to re-enter again. e.g. Nerve & Muscle cells

Front 10

Semi-Conservative Replication

Back 10

Half of the parent molecule is is retained by each daughter molecule (half is synthesized)

Front 11

Replication Forks

Back 11

Y-Shaped sites where the DNA duplex is being replicated in a bidirectional fashion

Front 12

Replicating chromosome in bacteria bind to . . .

Back 12

. . . the plasma membrane at their replication origins

Front 13

Bacterial cells divide by the process of

Back 13

Binary Fission

Front 14

Replicons

Back 14

Replication units. Replication of linear DNA molecules of eukaryotic chromosomes is initiated at multiple sites, creating replication units called replicons

Front 15

Origin of Replication

Back 15

A special DNA sequence at the center of each replicon where DNA synthesis is initiated by initiator proteins

Front 16

Origin Recognition Complex (ORC)

Back 16

A multi-subunit protein complex that binds to a replication origin

Front 17

Helicase

Back 17

An enzyme that unwinds the DNA double helix

Front 18

A-T base pairs are held together by . . .
G-C base pairs are held together by . . .

Back 18

A-T base pairs are held together by 2 hydrogen bonds
G-C base pairs are held together by 3 hydrogen bonds

Front 19

Replication Bubble

Back 19

Formed by two replication forks initiated at an origin that move away from each other

Front 20

Eukaryotes replicate DNA ______ than prokaryotes

Back 20

replicate DNA _slower_ than prokaryotes

Front 21

Licensing

Back 21

ensures that after DNA is replicated at any given replication origin during S phase, the DNA at that site does not become competent (licensed) for another round of replication until the cell has first pased through mitosis

Front 22

Cdk

Back 22

Cyclin-dependent Kinase

Front 23

DNA polymerase

Back 23

catalyzes the elongation of DNA chains at 3' end. Requires a small amount of DNA to act as a template

Front 24

Chain elongation occurs at the _' end of the DNA strand and grows in the _' -> _' direction

Back 24

Chain elongation occurs at the 3' end of the DNA strand and grows in the 5' -> 3' direction

Front 25

DNA Polymerase III

Back 25

DNA Polymerase found in Prokaryotes

Front 26

Substrates

Back 26

The 4 deoxynucleoside triphosphates

Front 27

Incoming nucleotides are covalently bonded to the _' ___ end of the growing chain

Back 27

ing nucleotides are covalently bonded to the 3' _-OH_ end of the growing chain

Front 28

Temperature-sensitive mutants

Back 28

cells that function properly at normal temperatures but become seriously impaired when the temperature is altered slightly

Front 29

DNA Polymerase involved in nuclear DNA replication in eukaryotes:

Back 29

α, δ, & ε

Front 30

DNA polymerase involved in DNA replication in mitochondria:

Back 30

γ

Front 31

In Eukaryotes, _ polymerase works on the leading strand

Back 31

In Eukaryotes, _δ_ polymerase works on the leading strand

Front 32

In Eukaryotes, _ polymerase works on the lagging strand

Back 32

In Eukaryotes, _ε_ polymerase works on the lagging strand

Front 33

Leading strand direction

Back 33

5' -> 3'; starts replication process before lagging strand

Front 34

Lagging strand direction

Back 34

3' -> 5'; discontinuous, but same process as leading strand

Front 35

Okazaki fragments

Back 35

pieces of DNA synthesized along the lagging strand

Front 36

DNA ligase

Back 36

Joins fragments of DNA

Front 37

Proofreading

Back 37

eliminates possibility of DNA polymerase going 3' -> 5'

Front 38

exonuclease

Back 38

enzymes that degrade DNA at end of chain

Front 39

Primase

Back 39

synthesizes a short RNA primer for DNA synthesis

Front 40

Proofreading cannot occur in the _' -> _' direction because . . .

Back 40

Proofreading cannot occur in the 5' -> 3' direction because there would be no free nucleotide triphosphate at a growing 5' end

Front 41

endonuclease

Back 41

enzymes that degrade DNA in the middle of the chain by making internal cuts

Front 42

Primase initiates RNA synthesis by joining two _________

Back 42

Primase initiates RNA synthesis by joining two _nucleotides_

Front 43

Primosome

Back 43

active complex of of primase & 6 other proteins in prokaryotes

Front 44

DNA Polymerase α

Back 44

Bound to primase, α initiates DNA replication

Front 45

DNA gyrase

Back 45

Prokaryotic topoisomerase that creates swivel points in DNA

Front 46

Single-stranded DNA binding protein (SSB)

Back 46

attach to exposed, single-strands of DNA to keep them unwound and accessible to DNA replication machinery. Fall off after replication

Front 47

Replisome

Back 47

the large complex of proteins involved in DNA replciation

Front 48

Telomeres

Back 48

Repeated sequence at the end of chromosomes that allow the ends to be replicated

Front 49

telomerase

Back 49

Finishes off gap at end of DNA molecules; lengthens lagging strand to leading strand

Front 50

Reverse transcriptase

Back 50

DNA polymerase enzyme that transcribes single-stranded RNA into double-stranded DNA

Front 51

PCR (Polymerase Chain-Reaction)

Back 51

a technique to amplify a single or few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence

Front 52

Mutation

Back 52

permanent change in DNA

Front 53

Spontaneous mutations

Back 53

Depurination & Deamination

Front 54

Depurination

Back 54

Removal of a Purine, leaving a sugar

Front 55

Deamination

Back 55

Removal of an amine (change in base) from cytosine to produce Uracil

Front 56

Thymine Dimer formation

Back 56

Induced mutation in which ultraviolet light induces covalent bonding between Ts in DNA

Front 57

Translesion synthesis

Back 57

Synthesis of new DNA across regions in which the DNA template is damaged

Front 58

Excision Repair

Back 58

correct DNA defects by cutting out defective nucleotides, replacing them and sealing them with DNA ligase

Front 59

Repair endonucleases

Back 59

Cleave the DNA backbone near a damaged site

Front 60

Mismatch repair

Back 60

Corrects non-complementary base pairs

Front 61

Homologous recombination

Back 61

Method for fixing double-strand breaks in one chromosome by using the good homologous chromosome as a template

Front 62

Five phases of Mitosis

Back 62

Prophase
ProMetaphase
Metaphase
Anaphase
Telophase

Front 63

Prophase

Back 63

Chromosomes condense
Two centrosomes separate to opposite ends of the nucleus
Mitotic Spindle begins to form

Front 64

Prometaphase

Back 64

Fragmentation of Nuclear Envelope
Spindle microtubules attach to kinetochores
Chromosomes being to move toward center of cell

Front 65

Centromere

Back 65

Constricted area where two the two members of each chromatid pair are held together

Front 66

Kinetochore

Back 66

Structure that attaches the paired chromatids to the spindle microtubules

Front 67

Kinetochore Microtubules

Back 67

Microtubules that attach to Kinetochores

Front 68

Polar Microtubules

Back 68

Microtubules that interact with microtubules from the opposite pole

Front 69

Astral Microtubules

Back 69

Shorter Microntubules that form asters at each pole

Front 70

Metaphase

Back 70

Fully condensed chromosomes align at metaphase plate

Front 71

Anaphase

Back 71

Two sister chromatids of each chromosome separate and begin moving toward opposite spindle poles

Front 72

Anaphase A

Back 72

Chromosomes are pulled, centromere first, toward the spindle poles as the kinetochore microtubules get shorter and shorter

Front 73

Anaphase B

Back 73

The poles themselves move away from each otheras the polar microtubules lengthen

Front 74

Telophase

Back 74

Daughter chromosomes arrive at the poles of the spindle and uncoil
Nucleoli develop
Spindle disassembles
Nuclear envelope forms
Cytokinesis begins

Front 75

Proteolysis

Back 75

Degradation of proteins by hydrolysis during Anaphase

Front 76

Topoisomerase during Anaphase

Back 76

Assists in the splitting of sister chromatids

Front 77

Cross-links

Back 77

Microtubules from each centrosome that lock together
Stabilize the ends of polar microtubules
Framework for the spindle

Front 78

Anaphase A chromosome movement

Back 78

Kinetochore motor proteins pull on microtubules
Microntubules depolymerize as they become exposed

Front 79

Cytokinesis in Animals

Back 79

Contractile ring of overlapping actin & myosin filaments pinches cell in two

Front 80

Cytokinesis in Plants

Back 80

Formation of a new cell wall, called a cell plate, inside the cell

Front 81

Phragmoplast

Back 81

in plants during cytokinesis, microtubules upon which the vesicles that carry carbs & proteins for the new cell wall travel

Front 82

Cell plate

Back 82

Cell wall during the process of formation

Front 83

Spindle assembly checkoint

Back 83

regulates the metaphase-to-anaphase transition

Front 84

G1 Checkpoint

Back 84

Point in late G1 when cell decides if it will continue in cell cycle.
Called "Start" in yeasts
Called "Restriction point" in animals

Front 85

Cyclin

Back 85

Activator protein

Front 86

Cyclin-Dependent Kinase (Cdk)

Back 86

Enzymes that require cycle to be activated. Progression of the cell cycle depends on Cdks

Front 87

Cohesin

Back 87

Adhesive proteins at the junction between sister chromatids. Degraded by separase.