Chapter 4 - Genetics Part I - Heredity and Reproduction

Question 1

asexual reproduction in prokaryotic vs. eukaryotic cells

Answer 1

prokaryotic: binary fission eukaryotic: mitosis

Question 2

heredity

Answer 2

passing of traits from parents to offspring

Question 3

gene

Answer 3

a segment of a DNA molecule that codes for a specific trait

Question 4

Describe the cloning process

Answer 4

• extract mature cell - harvest and enucleate egg - use electrical pulses to combine egg and cell - results in egg cell with donor nucleus that divides and turns into an embryo - embryo is inserted into surrogate organism - surrogate gives birth to clone

Question 5

Name 3 applications of cloning

Answer 5

agriculture & horticulture; GMOs; saving endangered/extinct species

Question 6

chiasmata

Answer 6

the site where homologous chromosomes cross and share genetic information

Question 7

What is the difference between a chromosome and a chromatid?

Answer 7

A chromosome is one “length” or DNA, unduplicated or duplicated; a sister chromatid is what you call each half in a duplicated chromosome

Question 8

chromatin

Answer 8

thread-like structures within a nucleus; a mass of chromosomes

Question 9

cloning

Answer 9

the process of producing an individual that is genetically identical to another using one cell

Question 10

What happens when crossing over occurs?

Answer 10

Segments of homologous chromosomes break and re-attach at similar locations, resulting in new combinations of offspring

Question 11

Diploid cells contain…

Answer 11

the normal amount of genetic information; 2 sets of chromosomes: one from each parent

Question 12

Other name for Down syndrome

Answer 12

Trisomy 21

Question 13

Other name for Edward’s syndrome

Answer 13

Trisomy 18

Question 14

fertilization

Answer 14

the formation of a zygote by the fusion of 2 gametes

Question 15

In humans, haploid gametes are called…

Answer 15

ova and sperm

Question 16

Define gametogenesis and identify 2 processes

Answer 16

Gametogenesis is the process in which cells undergo meiosis to produce gametes; oogenesis in female ovaries and spermatogenesis in male testes

Question 17

How many viable cells can oogenesis and spermatogenesis produce?

Answer 17

oogenesis - 1 viable cell and 3 polar bodies spermatogenesis - 4 viable cells

Question 18

homologous chromosomes

Answer 18

matching pairs of chromosomes that are similar in size and carry info for the same genes; just different versions of each other

Question 19

What do you call the location of a gene on a chromosome?

Answer 19

The location of the gene is referred to as the locus (s.) or loci (pl.)

Question 20

karyokinesis

Answer 20

the division of a cell nucleus during mitosis

Question 21

Describe interphase

Answer 21

duplication of chromosomes

Question 22

Describe the stages of mitosis.

Answer 22

Prophase - chromosomes shorten and thicken, nuclear membrane dissolves, and centrioles (small protein bodies) form spindle fibres

Metaphase - chromosomes align along the equator

Anaphase - centromeres divide and chromatids move to opposite ends of the cell

Telophase - chromosomes reach the poles and begin to unwind, spindle fibres dissolve, nuclear membrane forms

*cytokinesis is technically not part of mitosis - it is the second stage of cell division

Question 23

Describe Meiosis I.

Answer 23

Prophase I - nuclear membrane dissolves, centrioles form spindle fibres, chromosomes shorten & thicken, homologous chromosomes form tetrads, synapsis

Metaphase I - homologous chromosomes line up at equator, align centromeres across middle of cell

Anaphase I - one chromosome from each homologous pair moves to opposite poles; centromeres do not split

**Telophase I **- nuclear membrane forms, sometimes cytokinesis occurs, unlike mitosis chromosomes in each nuclei are not identical

*cells are now haploid

Question 24

What is a tetrad?

Answer 24

a pair of homologous chromosomes, each with 2 sister chromatids

Question 25

What is synapsis?

Answer 25

when chomatids intertwine with a matching chromatid during prophase I of meiosis

Question 26

Describe Meiosis II

Answer 26

* between meiosis I & II, DNA not duplicated and there is no interphase

**Prophase II **- chromosomes shorten & thicken, nuclear membrane dissolves, spindle fibres forms

Metaphase II - chromosomes (each with 2 sister chromatids) line up at equitorial plate, remaining attached at centromere

Anaphase II - sister chromatids separate and move to opposite ends of the cell

**Telophase II **- nuclear membrane reappears, division of cytoplasm follows

* results in 4 sex cells that are all genetically different

Question 27

What are sex chromosomes referring to?

Answer 27

Sex chromosomes are referring to the X and Y chromosomes; their combinations determine the sex ( 2X, 0Y = female; 1X, 1Y = male)

Question 28

What are somatic cells?

Answer 28

Body cells - any cell that is not a reproductive cell

Question 29

What are karyotypes?

Answer 29

visual arrangements of chromosomes; sorted based of size and shape

Question 30

In the human body, how many chromosomes do somatic cells and gametes have?

Answer 30

All somatic cells have 46 chromosomes (23 homologous pairs), which is the diploid number.

Gametes (sex cells) have 23 chromosomes, which is the haploid number.

Question 31

Turner’s syndrome

Answer 31

1 X and no Y chromosome

Question 32

Klinefelter syndrome

Answer 32

2 X and 1 Y chromosome

Question 33

Difference between a trisomy and a monosomy

Answer 33

In place of a homologous pair, a trisomy contains 3 chromosomes, and a monosomy contains only 1 chromosome

Question 34

What is non-disjunction?

Answer 34

failure of homologous pair of chromosomes to move to opposite poles during meiosis

Question 35

What is the sequence of a cell cycle?

Answer 35

G1 - S - G2 - mitosis - cytokinesis

Question 36

How does meiosis result in genetic variability?

Answer 36

1. Unique haploid cells meet with other unique haploid cells at fertilization
2. When crossing over occurs, genetic info. is swapped