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Bio > Lecture 11 > Flashcards

Lecture 11 Flashcards

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Biology 101 flashcards
1
Q

What are somatic cells

A

All cells that are not sperm or egg)

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2
Q

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

A

Half

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3
Q

What type of cell are gametes

A

Haploid

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4
Q

What do testes consist of

A

Highly coiled tubes called seminiferous tubules

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5
Q

Where are sperm cells produced

A

In particular cells found in seminiferous tubules

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6
Q

What secretes sex hormones (male)

A

Testes

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7
Q

What do the ovaries produce

A

Eggs, female sex hormones, estrogen, progesterone

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8
Q

Pathway of egg

A
  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
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9
Q

Where does fertilization occur

A

Uterine tube

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10
Q

Which organs are both in reproductive and endocrine system

A

Ovaries and testes

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11
Q

How are sex cells produced

A

Meiosis

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12
Q

Meiosis produces cells that

A
  1. Have half # of chromosomes of parent cell
  2. Genetically different
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13
Q

Why gametes have only 23 chromosomes

A

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

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14
Q

Which chromosomes come from mom/dad

A

Dad : X or Y
mom : X

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15
Q

What are all the cells except sex cells called

A

Autosomes
(We have 22 pairs of autosomes)

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16
Q

What is a homologous pair

A

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

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17
Q

Homologous chromosomes have

A

Same genes but may have different alleles

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18
Q

What are alleles

A

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

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19
Q

Job of meiosis

A

Convert diploid cells in ovaries or testes into haploid sex cells

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20
Q

How many daughter cells in meiosis

A

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

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21
Q

In prophase I :

A

Same as mitosis, but HOMOLOGOUS PAIRS LINE UP

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22
Q

What is crossing over

A

Paired homologous chromosomes exchange genetic material between nonsister chromatids

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23
Q

Result of crossing over

A

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

24
Q

Metaphase I :

A

PAIRS of homologous cell line up at metaphase plate

25
Q

Anaphase I :

A

Homologous pairs separate but chromatids remain attached

26
Q

Result of anaphase I

A

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

27
Q

Telophase I

A

Chromatids still attached, nuclear membrane reappears

28
Q

Cytokinesis I

A

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

29
Q

Overall of meiosis I

A

Crossing over and separation of homologous chromosomes,

30
Q

Goal of meiosis II

A

Separate sister chromatids

31
Q

Prophase II

A

Nuclear membrane disappears, spindles attach to kinetochore, centrosomes disappear

32
Q

Metaphase II

A

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

33
Q

Anaphase II

A

Sister chromatids separate

34
Q

Telophase II

A

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

35
Q

Cytokinesis of meiosis II

A

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

36
Q

What is the original source of genetic diversity

A

Mutations

37
Q

Mutations create diff versions of genes called

A

Alleles

38
Q

Reshuffling of alleles during sexual reproduction produces

A

New combinations of genes and increases genetic variation

39
Q

Behaviour of chromosomes during meiosis/fertilization is responsible for

A

Most of genetic variation

40
Q

Three mechanisms contributing to genetic variation

A
  1. Independent assortment of chromosomes(meiosis)
  2. Crossing over (meiosis)
  3. Random fertilization
41
Q

In meiosis I, homologous pairs orient how?

A

Randomly

42
Q

Crossing over produces what type of chromosomes

A

Recombinant (combine genes inherited from both parents)

43
Q

Where can crossing over occur in a chromosome

A

Anywhere

44
Q

The fusion of two gametes produces

A

A zygote with about 70 trillion diploid combinations

45
Q

What is nondisjunction

A

Failure of chromosomes to separate during meiosis

46
Q

What arise as a result of abnormal meiotic division

A

Aneuploidies

47
Q

Nondisjunction can occur in both…

A

Autosomes and sex chromosomes

48
Q

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

A

47 (1 extra chromosomes 21)

49
Q

Down syndrome characteristics

A

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

50
Q

Edward’s syndrome (extra chr 18)

A

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

51
Q

Patau syndrome (extra chr 13)

A

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

52
Q

Single X chr (lack of Y) makes

A

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

53
Q

Single Y chr with 2 or more X chr makes

A

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

54
Q

Is the Y or X chr required in humans

A

X chromosome

55
Q

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

A

A barr body (dense metabolically inactive X chr)

56
Q

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

A

Turns “off”

Bio (21 decks)

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