Chapter 10

Question 1

Bacteria divide by

Answer 1

binary fission. Asexual reproduction

Question 2

Bacterial genome

Answer 2

Single, circular chromosome tightly packed in the cell at the nucleoid region. (Prokaryotes don’t have nuclei). New chromosomes are partitioned to opposite ends of the cell

Question 3

Septum

Answer 3

Forms to divide cell into 2 cells
Protein FtsZ

Question 4

ORI. Termination site

Answer 4

Origin of replication of chromosomes

Question 5

Eukaryotes chromosomes

Answer 5

Linear chromosomes. Single or double armed

Question 6

Human chromosomes

Answer 6

46 chromosomes in 23 nearly identical pairs

Question 7

22 pairs

Answer 7

Autosomal (do nothing to determine sex)
XX=Female
XY= Male

Question 8

Typical human chromosome

Answer 8

Composed of chromatin complex of DNA and protein
140 million nucleotide long.
Over 2 meters of DNA inside a diploid human nucleus

Question 9

Heterochromatin

Answer 9

More condensed
Silenced or fewer genes (Methylated)
Gene poor (High AT content)
Stains darker

Question 10

Euchromatin

Answer 10

Less condensed
Gene expressing
Gene rich (Higher GC content)
Stains lighter

Question 11

Levels of Chromatin organization

Answer 11

1 Naked DNA
2 Nucleosome - first level of wrapping
3 Solenoid
4 Chromatin loops
5 Chromosomes

Question 12

Nucleosome

Answer 12

Complex of DNA and histone proteins (ball like)
DNA duplex coiled around 8 histone proteins every 200 nucleotides
Histones are positively charged. DNA phosphate groups (in nucleotide) negatively charged

Question 13

Solenoid

Answer 13

Nucleosomes wrapped into higher order coils
Leads to a fiber 30 nm diameter.
During mitosis chromatin in solenoid arranged around scaffold of protein to achieve maximum compaction

Question 14

Karyotype

Answer 14

Particular array of chromosomes in an individual organism. (Seeing genome)

Question 15

Diploid vs Haploid

Answer 15

Diploid (2n) 2 copies of all chromosomes, 1 from mom 1 from dad. Somatic cells- nothing to do with reproduction
Haploid (n) 1 set of chromosomes. Sperm or ovum. Sex or germ line cells

Question 16

Homologous

Answer 16

Pairs of chromosomes

Question 17

SRY region

Answer 17

Area that males turn on after the beginning and during the embryotic process

Question 18

Before DNA replication

Answer 18

each chromosome composed of a single DNA molecule (single armed) (monad)

Question 19

After DNA replication

Answer 19

each chromosome is composed of 2 identical DNA molecules, held together by cohesin proteins. One chromosome composed of 2 sister chromatids.

Question 20

Kinetochores

Answer 20

Microtubules attach to move chromosomes

Question 21

Human mitosis

Answer 21

Somatic cells. Growth, repair, regeneration. Start with one cell. One round of cell division. End with 2 identical new cells: Daughter cells.

Question 22

Eukaryotic cell cycle two phases

Answer 22

M phase/cytokinesis: Eukaryotic nuclear division (mitosis) and cell division (cytokinesis)
Interphase (bigger part) - Cell is being a cell, nucleus is visible, cell metabolic functions, including DNA replication, occur. Begins after cytokinesis and ends when mitosis starts.

Question 23

Interphase phases

Answer 23

G1 (Gap phase 1) - Growth of cell, longest phase. Primary growth phase
S (Synthesis) - Single to double arm. DNA replication create sister chromatids attached at centromere
G2 (Gap phase 2) - Some growth. Mostly preparation for M phase. Organelles replicate, microtubules organize, chromosomes coil more tightly

Question 24

Resting phase G0

Answer 24

Cells often pause in G1 before DNA replication and enter a resting state. Spend more or less time here before resuming cell division. Most cells in animal body are in G0. Muscle and nerve cells remain there permanently. Liver cells can resume G1 phase in response to factors during injury.

Question 25

Centromere

Answer 25

Point of constriction

Question 26

Kinetochore

Answer 26

Attachment site for microtubules

Question 27

Cohesin

Answer 27

Protein attachment for chromatids at centromere

Question 28

M (Mitosis) Phase

Answer 28

Prophase Prometaphase Metaphase Anaphase Telophase

Question 29

Prophase

Answer 29

Chromosomes condense and appear as two sister chromatids held together at the centromere. Nuclear envelope breaks down. Mitotic spindles (from centrioles) begin to form on opposite sides of cell. Asters-radial array of microtubules in animals (not plants. Golgi and ER are dispersed

Question 30

Prometaphase

Answer 30

After disassembly of nuclear envelope, chromosomes attach to microtubules at kinetochores from opposite poles and begin to move to equator

Question 31

Metaphase

Answer 31

Alignment of chromosomes along metaphase plate. Under tension from microtubules

Question 32

Anaphase

Answer 32

Begins when centromeres split. Removal of cohesin proteins. Sister chromatids pulled towards opposite poles. No longer chromatids, now chromosomes

Question 33

Telophase

Answer 33

Spindle apparatus disassembles, Nuclear Envelope forms. Chromosomes begin to uncoil and disperse. Nucleolus reappears. Golgi and ER reform

Question 34

Cytokensis

Answer 34

Cleavage of cell into equal halves. Animal cells constriction of actin filaments produces a cleavage furrow. Plants form cell plate between nuclei

Question 35

Control of cell cycle 2 concepts

Answer 35

1 Cycle has two irreversible points A. Replication of genetic material (S-phase) B. Separation of the sister chromatids (anaphase) 2. Cell can be put on hold at specific points called checkpoints. Process checked for accuracy, allows for response to internal and external signals

Question 36

3 Checkpoints

Answer 36

1. G1/S checkpoint - Decides whether or not to divide 2. G2/M checkpoints - Makes a commitment to mitosis, assesses success of DNA replication, can stall the cycle if DNA has not been accurately replicated 3. Late metaphase (Spindle Checkpoint) - Cell ensures that all chromosomes are attached to the spindles by microtubules.

Question 37

Cyclin-dependent kinases

Answer 37

(Cdks) Enzyme kinases that phosphorylates proteins (attaches phosphate group). Primary mechanism of cell cycle control. Cdks partner with different cyclins at different points in the cell cycle. Cdk itself controlled by phosphorylation.

Question 38

Cdk-cyclin complex

Answer 38

Also called Mitosis-promoting factor (MPF) promotes mitosis Activity of Cdk controlled by pattern of phosphorylation. Cdk has active and inactive sites for cyclin to bind to

Question 39

Anaphase-promoting complex (APC) Cyclosome (APC/C)

Answer 39

Function is to trigger anaphase itself. Marks securin for destruction. Securin inhibits separase (destroys cohesin). No securin = no inhibition of separase, separase destroys cohesin and sister chromatids can separate. APC marks securin for destruction

Question 40

Securin

Answer 40

Enzyme found in all cells. Secures cohesin and inhibits anaphase. Need to remove securin for anaphase to occur

Question 41

Separase

Answer 41

Enzyme that destroys cohesin once securin is is removed

Question 42

Cancer and two genes

Answer 42

Unrestrained, uncontrolled growth of cells. Failure of cell cycle control. Tumor suppressor genes Proto-oncogenes

Question 43

Tumor-suppressor genes

Answer 43

Genes whose activity includes preventing tumor formation (unwanted cell growth/division). Both copies of a tumor-suppressor gene must lose function for the cancerous phenotype to develop. p53: G1 checkpoint

Question 44

p53

Answer 44

G1 checkpoint monitors integrity of DNA and prevents the development of mutated cells. Abnormal p53 fails to stop cell division, damaged cells divide and cancer develops

Question 45

Proto-oncogenes

Answer 45

Normal cellular genes that become oncogenes when mutated. oncogenes can cause cell to be cancerous. Only one copy of proto-oncogene needs to undergo mutation for uncontrolled division to take place. Some proto-oncogenes encode receptors for growth factors, if receptor is mutated on, cell no longer depends on growth factors.