Midterm 2 (2.2)

Question 1

Meiosis

Answer 1

Type of eukaryotic cell division that produces sperm and eggs.

Meiosis reduces 2n to n
– Diploid to haploid

Meiosis makes cells genetically different from the parent cell AND each other

3 events unique to MEIOSIS (occur during MEIOSIS I)
-1. Synapsis and crossing over (during prophase I)
-2. Homologous pairs positioned at metaphase
plate
-3. Homologues separated

Question 2

Genome

Answer 2

Genetic material of an organism

Question 3

Chromosome

Answer 3

Packages DNA

Question 4

Somatic cells

Answer 4

All body cells except reproductive cells.

In humans: 46 chromosomes (two sets of 23)

Question 5

Gametes

Answer 5

Reproductive cells

Humans: 23 chromosomes (one set)

Question 6

Chromatids

Answer 6

Joined copies of original chromosome

Question 7

Centromere

Answer 7

Chromosomal DNA where sister chromatids most closely attached

Question 8

Arm of the chromatid

Answer 8

Portion of chromatid to either side of centromere

Question 9

Mitosis

Answer 9

Nuclear division in eukaryotic cells

1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase

Cytokinesis overlaps with latter stages, completes mitotic phase

Question 10

Cytokinesis

Answer 10

-Division of cytoplasm
-One cell becomes two

Question 11

Interphase

Answer 11

-G1 phase: cell grows
-S phase: cell grows and chromosomes replicated
-G2 phase: grows more, prepares for cell division

Question 12

Mitotic phase

Answer 12

Cell divides
-mitosis
-cytokinesis

Question 13

Interphase: G2

Answer 13

• Centrosome duplicated
  >2 centrosomes each with 2
  centrioles
• Chromosomes have been duplicated

Question 14

Prophase (mitosis)

Answer 14

Chromosomes condense
- two identical sister chromatids joined at centromere

Nucleoli disappear

Mitotic spindle forms
-centrosomes and microtubules

Centrosomes pushed away from each other

Question 15

Prometaphase (mitosis)

Answer 15

Nuclear envelope fragments

Each of the two chromatids now have a kinetochore

Microtubules attach to kinetochore

Question 16

Kinetochore

Answer 16

Protein structure at centromere

Question 17

Metaphase (mitosis)

Answer 17

Centrosomes at opposite poles

Chromosomes at metaphase plate
- Plane equidistant between two poles
- Centromeres at metaphase plate
- Kinetochore of each sister chromatid attached to microtubules from opposite poles

Question 18

Anaphase (mitosis)

Answer 18

Two sister chromatids pulled appart
-Each chromatid becomes a chromosome

Daughter chromosomes moved to opposite ends of cell as microtubules shorten

Cell elongated
-two ends of cell have complete copies of chromosome

Question 19

Telophase (mitosis)

Answer 19

2 daughter nuclei form

Nucleoli reappear

Chromosomes decondense

Spindle breaks down

Mitosis is finished

Question 20

Cytokinesis

Answer 20

Division of cytoplasm (starts during telophase)

Animal cells: cell pinches in two
- Occurs by CLEAVAGE
- Microfilaments contract until cell splits in two

Plant cells
- No cleavage furrow
- Cell plate produced by vesicles from Golgi during telophase.
- Cell plate develops into cell wall

Question 21

Aster

Answer 21

Radial array of shorter microtubules that extend from the centrosomes

Question 22

Metaphase plate

Answer 22

A plane that is equidistant between the spindle’s two poles.

Question 23

Asexual reproduction

Answer 23

Single individual is sole parent.

Parent passes copies of all its genes to offspring

No fusion of gametes

Some multi-cellular organisms can produce asexually

Question 24

Sexual reproduction

Answer 24

Two parents give rise to offspring that have unique combinations of genes inherited from both parents

Offspring vary genetically from siblings and parents

Question 25

Karyotype

Answer 25

Image of a cell’s chromosomes laid out in pairs

Question 26

Locus

Answer 26

Gene’s specific location along length of a chromosome (plural: loci)

Question 27

Homologous chromosomes OR homologues

Answer 27

Two chromosomes making up a pair have the same length, centromere position, staining pattern Both carry genes controlling the same inherited characters - If gene for eye colour is at a particular LOCUS on a certain chromosome. its homologue will have version of gene to specify eye colour (at same locus)

Question 28

Autosomes

Answer 28

Rest of the chromosomes that aren’t sex chromosomes

Question 29

Sex chromosomes

Answer 29

X and Y Females (XX) Males (XY) - Most genes on x do not have counterparts on Y - Y has genes X does not have

Question 30

Diploid cell

Answer 30

Any cell with 2 chromosome sets - Has diploid number of chromosomes (2n)

Question 31

n

Answer 31

Number of chromosomes in a single set

Question 32

Haploid cell

Answer 32

Single set of chromosomes (gametes) Haploid number of chromosomes (n)

Question 33

Fertilization

Answer 33

Union of haploid gametes to produce diploid zygote

Question 34

Allele

Answer 34

Different versions of genes in homologues - Allele for freckles on one chromosome and allele for absence of freckles at same locus on the homologue

Question 35

Synapsis

Answer 35

Paired homologues become physically attracted Form tetrads

Question 36

Chiasmata

Answer 36

Where a crossover has occurred

Question 37

Mutations

Answer 37

Original sources of genetic variation Changes in nucleotide sequence of an organism’s DNA or RNA of a virus Mutations created different versions of genes called alleles

Question 38

Recombinant chromosomes

Answer 38

Chromosomes that carry genes derived from 2 different parents