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BIO 1008 > reproduction genetics etc > Flashcards

reproduction genetics etc Flashcards

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1
Q

What is the purpose of mitosis vs meiosis?

A

Mitosis: growth and repair; Meiosis: gamete production.

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2
Q

How many cells result from mitosis vs meiosis, and what is their ploidy?

A

Mitosis: 2 diploid cells; Meiosis: 4 haploid cells.

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3
Q

Where does genetic variation occur in meiosis?

A

Crossing over in prophase I and independent assortment in metaphase I.

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4
Q

Where does fertilisation occur in the female reproductive system?

A

In the first third of the fallopian tube.

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5
Q

What role do fimbriae and cilia play in ovum transport?

A

Fimbriae direct the ovum, cilia move it into the fallopian tube.

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6
Q

What is the function of the cervix?

A

It is a muscular passage that dilates during childbirth (up to 10–12 cm).

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7
Q

Where is sperm produced and matured?

A

Produced in seminiferous tubules; matures in epididymis.

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8
Q

What does the seminal vesicle secrete?

A

Fructose (nourishes sperm), prostaglandins (motility), clotting agents.

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9
Q

What is the function of the prostate gland?

A

Secretes citric acid and proteolytic enzymes.

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10
Q

What is the function of the bulbourethral gland?

A

Secretes mucus and alkaline fluid to protect sperm.

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11
Q

What are the stages of spermatogenesis?

A

Spermatogonia → primary spermatocytes → secondary spermatocytes → spermatids → sperm.

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12
Q

What is the function of Sertoli cells?

A

Support and nourish developing germ cells.

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13
Q

What is capacitation?

A

Final maturation of sperm in the epididymis, prepares acrosome for fertilisation.

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14
Q

What is the function of the acrosome?

A

Contains enzymes to penetrate the egg.

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15
Q

What stage are oocytes arrested at birth?

A

Prophase I.

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16
Q

What triggers completion of Meiosis I in females?

A

LH surge during ovulation.

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17
Q

What is a polar body?

A

A small, non-functional product of meiosis that degenerates.

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18
Q

What is the role of the corpus luteum?

A

Secretes progesterone and some oestrogen after ovulation.

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19
Q

How many follicles typically mature in a woman’s lifetime?

A

Around 400.

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20
Q

What is the zona pellucida?

A

A glycoprotein layer around the oocyte that facilitates sperm entry.

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21
Q

When is Meiosis II completed in oogenesis?

A

Only if fertilisation occurs.

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22
Q

What hormonal change occurs in males at puberty?

A

Reduced sensitivity to testosterone/inhibin → ↑ GnRH, LH, FSH.

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23
Q

What does LH do in males?

A

Stimulates interstitial cells to produce testosterone.

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24
Q

What hormonal change triggers female puberty?

A

Maturation of the hypothalamus → ↑ GnRH → ↑ LH and FSH.

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25
What are the secondary sexual characteristics in females?
Breast development, fat redistribution, reproductive organ enlargement.
26
What are the secondary sexual characteristics in males?
Facial hair, voice deepening, testes enlargement.
27
What occurs during the Menses phase of the menstrual cycle?
Shedding of the endometrium if no implantation occurs (Days 1–5).
28
What stimulates follicle development in the proliferative phase?
FSH, triggered by GnRH from the hypothalamus.
29
What hormone thickens the endometrium during the proliferative phase?
Oestrogen, through mitosis.
30
What triggers ovulation?
LH surge around Day 14.
31
What is formed after the oocyte is released?
Corpus luteum.
32
What does the corpus luteum secrete?
Large amounts of progesterone, small amounts of oestrogen.
33
How does progesterone affect the menstrual cycle?
Thickens the endometrium and inhibits GnRH to prevent further ovulation.
34
What happens if fertilisation occurs?
Embryo implants; trophoblasts secrete hCG to maintain the corpus luteum.
35
What is the role of hCG?
Maintains corpus luteum and inhibits GnRH until the placenta forms.
36
What happens if fertilisation does not occur?
Corpus luteum degenerates; progesterone drops; GnRH rises and cycle restarts.
37
Where does fertilisation occur?
In the fallopian tube.
38
What is sperm capacitation?
Final maturation in the female tract that enhances motility and activates the acrosome.
39
How is polyspermy prevented?
Fast block (Na⁺ influx) and slow block (Ca²⁺-triggered cortical reaction).
40
What is a zygote?
The fused male and female pronuclei.
41
What is the zona pellucida?
A layer around the oocyte that prevents polyspermy and is shed during zona hatching.
42
What forms during cleavage?
A morula, which develops into a blastocyst.
43
What are the parts of a blastocyst?
Trophoblast (placenta) and inner cell mass (embryo).
44
When does implantation occur?
Days 7–10 after fertilisation.
45
What forms by Day 12?
Amniotic cavity, yolk sac, umbilical cord, embryonic disc.
46
What triggers gastrulation?
The primitive streak.
47
What are the 3 germ layers and their fates?
Ectoderm (skin, nerves), Mesoderm (muscles, organs), Endoderm (digestive tract).
48
What initiates neurulation?
Notochord signals ectoderm to form the neural tube (CNS).
49
What is the structure of the CNS?
Spinal cord: grey inside, white outside; Brain: white inside, grey outside.
50
When does organogenesis occur?
Weeks 3–8.
51
When is the embryo called a foetus?
From Week 9 onward.
52
How long is gestation?
About 280 days / 40 weeks / 9 months.
53
What happens during the first trimester?
Differentiation and organ rudiment formation.
54
What happens in the second and third trimesters?
Growth and maturation.
55
What initiates parturition (labour)?
Fetal ACTH, ↑ oestrogen, oxytocin, prostaglandins.
56
How does the positive feedback loop in labour work?
Cervical stretch → oxytocin → uterine contraction.
57
What is a gene?
A segment of DNA that encodes a protein.
58
What is an allele?
A variant of a gene due to differences in DNA sequence.
59
What is the difference between genotype and phenotype?
Genotype: allele combination (e.g., AA, Aa); Phenotype: observable traits.
60
What does homozygous mean?
Having two identical alleles (e.g., AA or aa).
61
What does heterozygous mean?
Having two different alleles (e.g., Aa).
62
How many pairs of chromosomes do humans have?
23 pairs (46 total); 22 autosomes and 1 pair of sex chromosomes.
63
What is the dominance pattern for the ABCC11 gene and earwax type?
G allele (wet earwax) is dominant; A allele (dry earwax) is recessive.
64
What is co-dominance?
Both alleles are fully expressed in the phenotype (e.g., AB blood type).
65
What is incomplete dominance?
Heterozygous phenotype is intermediate between homozygotes (e.g., sickle cell trait).
66
What are the genotypes and phenotypes for ABO blood types?
IAIA/IAi = A, IBIB/IBi = B, IAIB = AB, ii = O.
67
What is the genotype for sickle cell trait?
AS → mostly normal but can sickle under stress.
68
What is the genotype for sickle cell disease?
SS → abnormal red blood cells.
69
What is the result of a Punnett square for two GA (heterozygous) parents?
75% wet earwax (GG or GA), 25% dry earwax (AA).
70
How do you set up a dihybrid cross?
Use a 4x4 Punnett square to combine two traits (e.g., EeBb x EeBb).
71
What is the probability of ee and B_ in a dihybrid cross of EeBb x EeBb?
3/16 or 18.75%.
72
What symbols are used in a pedigree chart?
◯ = unaffected female, ⬤ = affected female, ⬜ = unaffected male, ⬛ = affected male.
73
What does it mean if a child has sickle cell disease and both parents are carriers?
Each parent must have the S allele (heterozygous AS).
74
What inheritance pattern is seen in Huntington’s disease?
Autosomal dominant.
75
What genotypes are affected in Huntington's disease?
Hh and HH.
76
What is the probability of passing on Huntington’s if one parent is Hh and the other is hh?
0.5
77
What determines biological sex in humans?
XX = female, XY = male; SRY gene on Y triggers male development.
78
What is X-linked recessive inheritance?
Trait caused by gene on X chromosome; males more affected as they have only one X.
79
What are the genotypes and phenotypes in X-linked recessive inheritance?
XaXa = affected female, XAXa = carrier female, XaY = affected male.
80
Why are males more affected by X-linked recessive disorders?
They have only one X chromosome, so one recessive allele causes the condition.
81
What are examples of X-linked recessive disorders?
Red-green colour blindness, Haemophilia A/B, G6PD deficiency.
82
What is X-inactivation (Lyonisation)?
Random silencing of one X chromosome in females early in development.
83
What causes symptoms in some female carriers of X-linked disorders?
Skewed X-inactivation toward the normal X chromosome.
84
How is severity determined in G6PD deficiency?
By the percentage of RBCs with the deficient enzyme.
85
What is X-linked dominant inheritance?
Trait is dominant on the X chromosome; affects both sexes.
86
What are the genotypes and phenotypes for X-linked dominant traits?
XAXA and XAXa = affected female, XAY = affected male, XaXa = unaffected female.
87
What is the inheritance pattern for X-linked dominant traits?
Affected fathers pass trait to all daughters, not sons. Affected mothers pass to 50% of children.
88
Example of an X-linked dominant disorder?
Ornithine transcarbamylase (OTC) deficiency.
89
What is Y-linked inheritance?
Trait carried on Y chromosome; only affects males; passed from father to all sons.
90
Example of Y-linked disorder?
AZF microdeletion → causes male infertility.
91
In a pedigree, how do X-linked recessive traits typically appear?
Trait appears in males, skips generations, passed through carrier females.
92
In a pedigree, what does an affected father with X-linked dominant disorder pass to children?
All daughters affected, no sons.
93
What symbols are used in pedigrees?
◯ = unaffected female, ⬤ = affected female, ⬜ = unaffected male, ⬛ = affected male.
94
What is the inheritance pattern for Y-linked traits?
Only males affected; passed father to all sons.
95
Summary: Who is affected in X-linked recessive inheritance?
Mainly males; inherited from carrier mothers.
96
Summary: Who is affected in X-linked dominant inheritance?
Both sexes; affected father → all daughters, affected mother → 50% of kids.

BIO 1008 (9 decks)

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