Chromosomes And Cellular Reproduction

Question 1

What is a prokaryote? (3 items)

Answer 1

Unicellular with no compartmentalized cell structure.
DNA is circular and not highly packed.
Made up of eubacteria and archaebacteria.

Question 2

How do prokaryotes replicate? (3 items)

Answer 2

Simple division: separation of replicated circular chromosome
Single origin of replication
High rate of replication

Question 3

What is a eukaryote? (3)

Answer 3

Both unicellular and multicellular with compartmentalized cell structure.
DNA resides in the nucleus.
DNA is wrapped around histones to form tightly packed chromosomes.

Question 4

Number of human chromosomes (1)

Answer 4

23 pairs = 46 chromosomes.

Question 5

Chromosome structure (3)

Answer 5

Centromere - attachment point for spindle microtubules
Telomeres - tip of a linear chromosome
Origins of replication - where DNA synthesis begins

Question 6

Chromatid (1)

Answer 6

One half of a paired chromosome (can also be called a chromosome)

Question 7

Interphase (1)

Answer 7

Cell growth

Question 8

Stages of interphase (3)

Answer 8

G1, S, G2

Question 9

G1 (1)

Answer 9

Cell growth

Question 10

G0 (3)

Answer 10

Non-dividing phase
Occurs when errors are present
Often leads to apoptosis

Question 11

G1/S checkpoint (2)

Answer 11

DNA error checking point before entering S phase

Cancer blows through this checkpoint

Question 12

S Phase (1)

Answer 12

DNA synthesis phase

Question 13

G2 (1)

Answer 13

Mitosis preparation

Question 14

G2/M checkpoint (1)

Answer 14

Last checkpoint before mitosis

Question 15

M phase (1)

Answer 15

Mitosis and cytokinesis

Question 16

Genetic consequences of the cell cycle (3)

Answer 16

Produces two cells that are genetically identical to each other
New cells contain a full complement of chromosomes
Each new cell contains approximately half (but not necessarily identical) the cytoplasm and organelle content of the original parental cell

Question 17

Stages of Mitosis (5)

Answer 17

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

Question 18

Interphase (2)

Answer 18

Nuclear membrane is present

Chromosomes are relaxed

Question 19

Prophase (3)

Answer 19

Chromosomes condense
Each chromosome possesses two chromatids
Centrosomes and mitotic spindles forms

Question 20

Prometaphase (2)

Answer 20

Nuclear membrane disintegrates

Spindle microtubules attach to chromatids

Question 21

Metaphase (1)

Answer 21

Chromsomes line up on the metaphase plate

Question 22

Anaphase (1)

Answer 22

Sister chromatids separate and move toward opposite poles

Question 23

Telophase (3)

Answer 23

Chromosomes arrive at the spindle poles
Nuclear membrane reforms
Chromosomes relax

Question 24

Cytokinesis (2)

Answer 24

Cytoplasm divides

Cell membranes close

Question 25

Cohesin (1)

Answer 25

Controls the separation of chromatids in mitosis and meiosis

Question 26

Shugoshin (1)

Answer 26

Protects the breakdown of cohesin near the centromere

Question 27

Stages of Prophase I (5)

Answer 27

``` Leptotene Zygotene Pachytene Diplotene Diakinesis ```

Question 28

Leptotene (1)

Answer 28

Chromosomes contract and become visible

Question 29

Zygotene (4)

Answer 29

Chromosomes continue to condense Homologous chromosomes pair up Homologous chromosomes begin synapsis - a very close pairing association Each pair of chromosomes has four sister chromatids called a bivalent or tetrad.

Question 30

Pachytene (2)

Answer 30

Continued condensation | Formation of synaptonemal complex

Question 31

Crossing over (2)

Answer 31

Crossing over of chromosome segments from the sister chromatid of one chromosome to the sister chromatid of the other synapsed chromsome Can occur in zygotene, pachytene, or diplotene phases, but mostly pachytene

Question 32

Diplotene (2)

Answer 32

Centromeres move apart | Chromosome still attached at each chiasma

Question 33

Diakinesis (4)

Answer 33

Continued chromosome condensation Chiasmata move to tips of chromosomes Nuclear membrane breaks down Meiotic spindle forms

Question 34

Metaphase I (1)

Answer 34

Homologous pairs of chromosomes line up along the metaphase plate

Question 35

Anaphase I (2)

Answer 35

separation of homologous chromosome pairs | Random distribution of chromosomes into two newly divided cells

Question 36

Telophase I (3)

Answer 36

Chromosomes arrive at opposite poles The cytoplasm divides. Chromosomes relax.

Question 37

Prophase II (1)

Answer 37

Chromsomes recondense

Question 38

Stages of Meiosis (3)

Answer 38

Interphase - DNA synthesis and chromosome replication Meiosis I - separation of homologous pairs and reduction of chromosome number by half Meiosis II separation of sister chromatids

Question 39

Metaphase II

Answer 39

Individual chromosomes line up along equatorial plate.

Question 40

Anaphase II (1)

Answer 40

Sister chromatids separate and move toward the opposite poles.

Question 41

Telophase II (2)

Answer 41

Chrosomes arrive at spindle poles | Cytoplasm divides

Question 42

Consequences of Meiosis and Genetic Variation (3)

Answer 42

Four cells are produced from the original cell Chromosome number in each new cell is reduced by half - new cells are all haploid. New cells are genetically different from one another and from the parental cell.