Lecture 11

Question 1

What are somatic cells

Answer 1

All cells that are not sperm or egg)

Question 2

Gametes contain how much of the genetic material necessary to form a complete organism

Answer 2

Half

Question 3

What type of cell are gametes

Answer 3

Haploid

Question 4

What do testes consist of

Answer 4

Highly coiled tubes called seminiferous tubules

Question 5

Where are sperm cells produced

Answer 5

In particular cells found in seminiferous tubules

Question 6

What secretes sex hormones (male)

Answer 6

Testes

Question 7

What do the ovaries produce

Answer 7

Eggs, female sex hormones, estrogen, progesterone

Question 8

Pathway of egg

Answer 8

1. Released from ovary (ovulation)
2. Fimbriae of uterine tube catches it
3. Cilia in uterine tube moves it down to uterus
4. Egg exits uterus via cervix
5. Opening in cervix leads it to vagina

Question 9

Where does fertilization occur

Answer 9

Uterine tube

Question 10

Which organs are both in reproductive and endocrine system

Answer 10

Ovaries and testes

Question 11

How are sex cells produced

Answer 11

Meiosis

Question 12

Meiosis produces cells that

Answer 12

1. Have half # of chromosomes of parent cell
2. Genetically different

Question 13

Why gametes have only 23 chromosomes

Answer 13

Bc when female + male combine = 46 chromosomes (normal cell, or else 92)

Question 14

Which chromosomes come from mom/dad

Answer 14

Dad : X or Y
mom : X

Question 15

What are all the cells except sex cells called

Answer 15

Autosomes
(We have 22 pairs of autosomes)

Question 16

What is a homologous pair

Answer 16

When two chromosomes have same genes (ex: pair #1 of karyotype)

Question 17

Homologous chromosomes have

Answer 17

Same genes but may have different alleles

Question 18

What are alleles

Answer 18

Alternative versions of genes (ex same gene but one codes for blue eyes and other brown)

Question 19

Job of meiosis

Answer 19

Convert diploid cells in ovaries or testes into haploid sex cells

Question 20

How many daughter cells in meiosis

Answer 20

After meiosis I : 2 daughter cells
After meiosis II : 4 daughter cells

Question 21

In prophase I :

Answer 21

Same as mitosis, but HOMOLOGOUS PAIRS LINE UP

Question 22

What is crossing over

Answer 22

Paired homologous chromosomes exchange genetic material between nonsister chromatids

Question 23

Result of crossing over

Answer 23

Chromosomes will have same # genes but sister chromatids are no longer identical

Question 24

Metaphase I :

Answer 24

PAIRS of homologous cell line up at metaphase plate

Question 25

Anaphase I :

Answer 25

Homologous pairs separate but chromatids remain attached

Question 26

Result of anaphase I

Answer 26

Bc homologous pair separate, ends of cell have 1 set of chromosomes meaning: diploid -> haploid

Question 27

Telophase I

Answer 27

Chromatids still attached, nuclear membrane reappears

Question 28

Cytokinesis I

Answer 28

Daughter cells have both copies of ONE kind of chromosome, haploid and genetically diff from each other

Question 29

Overall of meiosis I

Answer 29

Crossing over and separation of homologous chromosomes,

Question 30

Goal of meiosis II

Answer 30

Separate sister chromatids

Question 31

Prophase II

Answer 31

Nuclear membrane disappears, spindles attach to kinetochore, centrosomes disappear

Question 32

Metaphase II

Answer 32

Chromosomes line up in middle ( sister chromatids are diff bc of crossing over)

Question 33

Anaphase II

Answer 33

Sister chromatids separate

Question 34

Telophase II

Answer 34

Nuclear membrane forms, haploid set of chromosomes on each side of the

Question 35

Cytokinesis of meiosis II

Answer 35

Each cell divides into total of 4, each have single copy of chromosomes

Question 36

What is the original source of genetic diversity

Answer 36

Mutations

Question 37

Mutations create diff versions of genes called

Answer 37

Alleles

Question 38

Reshuffling of alleles during sexual reproduction produces

Answer 38

New combinations of genes and increases genetic variation

Question 39

Behaviour of chromosomes during meiosis/fertilization is responsible for

Answer 39

Most of genetic variation

Question 40

Three mechanisms contributing to genetic variation

Answer 40

1. Independent assortment of chromosomes(meiosis) 2. Crossing over (meiosis) 3. Random fertilization

Question 41

In meiosis I, homologous pairs orient how?

Answer 41

Randomly

Question 42

Crossing over produces what type of chromosomes

Answer 42

Recombinant (combine genes inherited from both parents)

Question 43

Where can crossing over occur in a chromosome

Answer 43

Anywhere

Question 44

The fusion of two gametes produces

Answer 44

A zygote with about 70 trillion diploid combinations

Question 45

What is nondisjunction

Answer 45

Failure of chromosomes to separate during meiosis

Question 46

What arise as a result of abnormal meiotic division

Answer 46

Aneuploidies

Question 47

Nondisjunction can occur in both...

Answer 47

Autosomes and sex chromosomes

Question 48

Down syndrome/trisomy 21/autosomal aneuploidy has how many chromosomes

Answer 48

47 (1 extra chromosomes 21)

Question 49

Down syndrome characteristics

Answer 49

Highest rate of occurrence of genetic disorders More from maternal distinctions Genes on chromosomes 21 over-expressed

Question 50

Edward's syndrome (extra chr 18)

Answer 50

-affect all systems of body -about 95% of fetuses die before birth -infants have 5% chance to survive to age 1

Question 51

Patau syndrome (extra chr 13)

Answer 51

85% of 15% survivors past one month dot survive past 1yo Most fetuses die before birth

Question 52

Single X chr (lack of Y) makes

Answer 52

Females with Turner's syndrome (Less developed breast/ovaries, no puberty)

Question 53

Single Y chr with 2 or more X chr makes

Answer 53

Males (bc Y chr) with Klienfelter syndrome (feminine features, less developed testes)

Question 54

Is the Y or X chr required in humans

Answer 54

X chromosome

Question 55

One X chr is inactivated in humans so the extra X is

Answer 55

A barr body (dense metabolically inactive X chr)

Question 56

Barr bodies explain why extra X chr is not severe compared to extra autosome as it

Answer 56

Turns "off"