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BIOL 207 > Lec 11-1 > Flashcards

Lec 11-1 Flashcards

1
Q

Two processes of sexual reproduction

A

Meiosis and fertilization

Cycle between the two leads to alternation of haploid and diploid cells

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2
Q

Most organisms have

A

Two sexes

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3
Q

Biological sex

A

Sexual phenotypes

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4
Q

Males produce

A

Small gametes

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5
Q

Females produce

A

Large gametes

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6
Q

Gender

A

Category assigned by the individual (identity) or other based on behavioral and cultural practices

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7
Q

Monoecious Hermaphroditism

A

Male and female at the same time

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8
Q

Diocious

A

Male or female

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9
Q

Sex determination

A

Biological mechanisms that regulate sexual phenotypes

Remarkably, the mechanisms of sex determination varies wildly across different organisms

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10
Q

Sex determination methods

A

Chromosomally

Genetically

Environmentally

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11
Q

Chromosomal sex determining systems

A

Sex is determined by the presence of a few sex chromosomes

Autosomes (non-sex chromosomes) vs sex chromosomes

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12
Q

Most XX-XY species

A

Female is XX male is XY

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13
Q

Y chromosome

A

Y shaped and acrocentric- one chromosome arm is much shorter than the other

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14
Q

XX-XY system

A

Like homologous autosomes

Sex chromosomes pair during metaphase and segregate independently

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15
Q

Sex chromosomes and autosomes pair because

A

They are homologous in small regions called pseudo autosomal regions

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16
Q

Crossing a male and a female from the XX-XY system produces a

A

1:1 male and female progeny

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17
Q

Males are the

A

Heterogametic sex

18
Q

Females are

A

The homogametic sex

19
Q

XX-XO system

A

System found in grasshoppers and is simplest sex determination system

Females- XX

Males- X(O)

O indicates lack of sex chromosome

20
Q

XX-XO generates

A

1:1 ratio in sex

21
Q

ZZ-ZW system

A

Found in bearded dragons and birds

Females- heterogametic
Males- Homogametic

Z and W are used to prevent confusion

22
Q

Sex in the chromosomal sex-determining systems is determined by

A

Individual genes located on sex chromosomes working in conjunction with genes on autosomes

23
Q

Genic sex determination

A

Some organisms have no obvious differences in the chromosomes between males and females

These organisms have genic sex determination

Genotypes at one or more loci determine the sex of an individual without specific sex chromosomes

24
Q

Environmental sex determination

A

Number of organisms determine sex based on environmental factors

25
Q

Marine mollusks

A

First mollusks to attach to a free substrate are female

A new male mollusk is attracted to chemicals released by female

they mate

Overtime the male mollusk becomes female

Another male is attracted to this female and the process repeats

26
Q

Sequential hermaphroditism

A

Each individual can be both male and female but not at the same time

27
Q

Temperature can determine sex during

A

Embryonic development in many turtles, crocodiles and alligators

Other animals like bearded dragons use sex chromosomes but temperature can override this

28
Q

Calvin Bridges XX-XY system

A

Proposed that in fruit flies sex was determined not by the amount of X and Y chromosomes but instead the balance between

female determining genes on X

male-determining genes on the autosomes

29
Q

Bridges proposed that fly sex is determined by

A

X:A ratio (number of X chromosomes divided by number of haploid sets of autosomes)

30
Q

Normal flies have 2 haploid sets of autosomes and 2X for females and 1X for males, so

A

Normal male X:A = 1/2 = .5
Normal female X:A = 2/2 = 1

31
Q

Autosome numbers indirectly affect

A

developmental timing and X linked gene expression.

32
Q

XX-XY system humans

A

Drosophila and humans share XX-XY

However, unlike drosophila the y chromosome determines sex in humans

Male determining region is mapped on the Y chromosome

33
Q

SRY

A

Sex determining Region Y gene

Genetic engineering in mice placed just the SRY gene in XX mice and these mice were anatomically male

34
Q

Role of sex chromosomes in humans

A

X chromosome contains genes essential for both sexes

Male-determining gene on the Y (even if extra X chromosomes, if there is a Y they are likely a male)

Absence of Y leads to female sex

Fertility genes located on X and Y

Additional X chromosomes can upset normal development of males or females

35
Q

Turner Syndrome

A

Genotype- XO

Female with underdeveloped secondary sex characteristics

36
Q

Klinefelter syndrome

A

XXY or XXXY

Men with small testis, reduce facial and pubic hair, sterile, tall

Normal intelligence

37
Q

Poly-X females

A

Triple-X syndrome

XXX

No distinctive features other than tendency to be tall/thin

Intellectually disability risk is increased

Some have 4 or 5 Xs and intellectual and physical disabilities

38
Q

Androgen-insensitivity syndrome

A

Normal male chromosome (XY)

But

Female external sexual characteristics but fail to menstruate.
Vagina but no uterus, oviducts, or ovaries.

Inside abdominal cavity have pair of testis that makes
testosterone similar to males.

39
Q

How does a person appear female but have a Y and testis that
make testosterone?

A

The SRY gene causes testis to develop and produce testosterone

Normally testosterone makes tissues develop male characteristics by binding and activating the androgen receptor

People with Androgen-Insensitivity Syndrome are defective in this androgen receptor, leading to female characteristics

40
Q

Androgen receptor gene is located on the

A

X chromosome and is inherited from the mother

BIOL 207 (31 decks)

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