Meiosis

Question 1

What does diploid mean

Answer 1

Cell that contains 2 copies of each chromosome

Question 2

Somatic cells

Answer 2

Body tissues which undergo mitosis

Question 3

Haploid

Answer 3

A cell which contains 1 copy of each chromosome

Question 4

Gamete

Answer 4

A reproductive cell that is formed through meiosis (sperm, ovum)

Question 5

Germ line cell

Answer 5

Reproductive cells responsible for gametogenosis (formation of gamete’s) in humans the 23 pairs of chromosomes are referred to as homologous

Question 6

Homologous chromosome

Answer 6

Pairs of chromosomes that have the same length, centromere location, genes, and banding pattern when stained with specific dyes

Not identical to each other, but contain genes that code for same trait

Question 7

Meiosis

Answer 7

Process by which sex cells or gametes are formed, occurs in testes and ovaries in humans

Involves 2 nuclear divisions

Results in the 4 daughter cells having half the number of chromosomes as the original parent cell (haploid)

Question 8

Meiosis I?

Answer 8

Called reduction division because the diploid chromosome number is reduced to haploid

Question 9

What is happening in prophase I?

Answer 9

Nuclear envelope begins to dissolve, centrioles move to opposite poles and spindle fibres form

Homologous chromosomes are held tightly along their lengths referred to as synapsis (foursome of chromatids)

Crossing over happens

Question 10

What is crossing over?

Answer 10

Process whereby the chromosomes synapse, chromosomes intertwine and break and exchange segments

Permits exchange if genetic info = genetic variation

Question 11

Metaphase I (meiosis)

Answer 11

Homologous chromosomes attach to spindle fibres and line up at equatorial plate

Question 12

Anaphase I (meiosis)

Answer 12

Homologous chromosomes move towards opposite poles = segregation

One member of each homologous pair will be found in each new cell

Reducing chromosome number from 2n to n

Question 13

Telophase I (meiosis)

Answer 13

Membrane forms around each nucleus, 2 nuclei are not identical as each daughter cell contains one member of the chromosome pair.

Question 14

Meiosis II

Answer 14

Marked by separation of 2 chromatids

Question 15

Prophase II (meiosis)

Answer 15

Nuclear envelope dissolves and spindle fibres begin to form

Signals beginning of 2nd division

Question 16

Metaphase II

Answer 16

Chromosome line up at the equatorial plate

Question 17

Anaphase II (meiosis)

Answer 17

Sister chromatids of each chromosome seperate and move to opposite poles

Question 18

Telophase II

Answer 18

Second nuclear division is completed, nuclear envelope begins to form around chromosomes, 2nd division of cytoplasm occurs, 4 haploid daughter cells are produced

Question 19

Mutation

Answer 19

Change in DNA sequence of a gene

Question 20

Gametic mutation

Answer 20

Mutations can be inherited, parents can pass on genetic mutation to their children if mutation occurs in gamete’s, increasing frequency within population

Question 21

Somatic mutation

Answer 21

Mutations can be accquired, 2 types

Spontaneous: mutations that arise in nature, no specific agent other than natural processes. Associated w occurance. Eg misetaje occurs when cell copies its DNA before cell division

Induced: mutations that arise from external factors, chemical, exposure, non-naturally occurring radiation exposure, virusus

Eg uv radiation.

Not passed on

Question 22

2 categories of mutations

Answer 22

Changes in chromosome structure

Changes in number =no disjunction

Question 23

Deletion

Answer 23

Section of chromosome is deleted, happens in S phase

Eg 22q11, heart defects

Question 24

Duplication

Answer 24

Section KF a chromosome appears 2 or more times in a row, results in larger number of copies of gene

S ohase

Fragile X syndrome, development issues

Question 25

Inversion

Answer 25

A section of chromosome is inverted (reversed) during crossing over, no genetic material gained or lost, can alter sequence of a gene making it no longer functional

Chromosome 9, inversion syndrome

Question 26

Translocation

Answer 26

Swapping a portion of a chromosome with a non-homologous chromosome

Crossing over w nkt its pair

Robertsonian translocation, no visible symptoms

Question 27

Errors in chromosome number

Answer 27

Non disjunction disorder

When chromosomes are separated during meiosis can cause errors, when 2 homologous chromosomes move to same pole during meiosis or when sister chromatids don’t seperate , when it results in one cell too little it’s called nondisimjumction,

Question 28

Monosomy

Answer 28

When gamete w 22 chromosomes combines with a normal gamete (23) the zygote will contain 45 chromosomes, only 1 copy of certain chromosome

Question 29

Trisomy

Answer 29

When gamete w 24 chromosomes combines with a normal gamete the zygote will contain 47 chromosomes, 3 copies of certain chromosomes, normal: 2

Question 30

What 2 processes occur in meiosis which increase genetic diversity

Answer 30

1. Crossing over : in prophase 1, exchange if alleles btw non sister chromatids. Similar alleles transferred
2. Independent assortment: occurs when genes from parents are assorted randomly,

different genes separate independently from another,

results in chromosomes lining up randomly,

creates cells w diff combinations of alleles from both maternal and paternal chromosome

Question 31

Synapsis

Answer 31

When homologous chromosomes come together to cross over (foursome of chromatids) or tetrad

Question 32

Karyotype

Answer 32

Staining and photographing chromosomes during mitosis, done during pregnancy to test for genetic disorder’s.

2 techniques: cvs (chronic villi sampling) and amniocentesis

CVS: invoked sampling chronic villi which is what connects placenta to mothers uterus lining

Amniocentesis: involves removing from of the the cells that are floating in amniotic fluids