Problem 1: Birds and the bees Flashcards

1
Q

Genotype

A

Genetic material inherited

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2
Q

Phenotype

A

Observable characteristics and behaviors that arise from a combination of our genotype and the environment

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3
Q

Chromosome

A

Chromosomes:
- 23 pairs similar in shape, size, and genetic function (excluding XY).
- 50/50 from both parents.
- The first 22 pairs are autosomes and are homologous (the same) and the 23rd pair is the sex chromosome (XY)

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4
Q

DNA

A

Double helix molecule connected by nucleotide
- Adenine
- Thymine
- Cytosine
- Guanine
A and T bind together, and C and G too.

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5
Q

Homozygous vs Heterozygous

A

Homozygous: equal alleles passed on from both parents.
Heterozygous: alleles differ between parents.

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6
Q

Conception

A

Fertilization > ovum > uterus > fallopian tube > fertilized by sperm > zygote

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7
Q

Mitosis (cell division)

A
  • From 1 to 2, then 2 to 4, then 4 to 8, etc.
  • Chromosomes split > duplication of the chromosomes (23 to 46) > they move to opposite sides > division of the cell (identical sets)
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8
Q

Meiosis (cell division)

A
  • Only for sex chromosomes (germ cells)
  • They produce gametes
  • Duplication of the 23 chromosomes (46) > crossing-over > new unique hereditary combination
  • Independent assortment: millions of different combinations.
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9
Q

Monozygotic vs Dyzygotic twins

A

Monozygotic: 100% identical, one zygote split into two identical cells.
Dygotic: Fraternal, two zygotes from two sperms, 50% identical.

  • 22 out of the 23 chromosomes are the same in both females and males.
  • The 23rd chromosome defines sex: Males: XY, Females: XX
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10
Q

Single-gene inheritance

A

Characteristics influenced by one pair (one allele from the mother, one from the father).
- Dominant vs recessive traits.

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11
Q

Co-dominance inheritance

A

Phenotype of the gene is a compromise between two dominant genes.

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12
Q

Sex-linked inheritance

A
  • Traits located on the X sex chromosomes.
  • More common in Males (females counteract the traits by having two X chromosomes unless the allele is dominant in both).
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13
Q

Hereditary disorders: congenital defects

A
  • Effects present at birth but not detectable right away.
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14
Q

Chromosomal abnormalities: Sex chromosomes (Poly X and Poly Y)

A
  1. Poly X: 1 in 1000 female births, fertile, low IQ, normal phenotypically
  2. Poly-Y: 1 in 1000 male births, fertile, low sperm count, normal phenotypically.
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15
Q

Chromosomal abnormalities: sex chromosomes (Klinefelter’s syndrome - males)

A
  • 1 in 1000 births, XXY, feminine traits, phenotypically male, sterile, poor cognitive abilities.
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16
Q

Chromosomal abnormalities: sex chromosomes (Turner’s syndrome XO)

A
  • 1 in 2500 births (females)
  • Sterile, normal IQ, one chromosome is missing.
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17
Q

Chromosomal abnormalities: sex chromosomes (Fragile X syndrome)

A
  • Anomaly in the X chromosome.
  • Common in males more than females, normal, prominent ears/legs, etc.
18
Q

Chromosomal abnormalities: autosomes

A
  1. Down syndrome: extra part of a 21st chromosome (failed to disconnect during meiosis). Intellectually impaired, spokes problems, protruding tongue. 1 in 800 births.
19
Q

Genetic abnormalities: Phenylketonuria (PKU)

A

1 in 10,000/20,000 births, lack of enzymes to digest food, mental retardation, etc.

20
Q

Genetic abnormalities: Huntington’s disease

A
  • Stops the brain from working over time.
  • 1 in 18,000/20,000 births
  • Inherited from a dominant allele
  • 50% chance for children
  • Symptoms: depression, poor motor skills, premature deaths, starts at 40.
21
Q

Genetic abnormalities: Sickle cell anemia

A

1 in 500 births, abnormal red blood cells, inefficient distribution of oxygen.

22
Q

The prenatal stages: conception

A
  • Begins with fertilization.
  • Once every 28 days, an ovum is released from one of the two ovaries and one of the two fallopian tubes is retracted.
  • The ovum-released site, the corpus luteum, produces hormones that prepare the uterine wall for conception.
  • The males’ testicles produce sperm that develop a tail that swims up the female reproductive system to the fallopian tubes where conception happens.
  • Prenatal development starts with conception, lasts around 38 weeks, and can be divided into three periods:
    1. The zygote period
    2. The embryo period
    3. The foetus period
23
Q

Period of the Zygote

A
  • The first two weeks.
  • Germinal or zygote period.
  • Zygote is a fertilised ovum.
  • The zygote moves from the fallopian tubes to the wall of the uterus and cell division (mitosis) takes place.
  • The cell division creates two parts:
    1. the Blastocyst: a group of 60 to 70 cells that form a hollow, fluid-filled ball. The inner cells are called the embryonic disk, which will become the new organism.
    2. The trophoblast: the outer layer of cells that provide the embryo with nutrition and protection.
  • Implantation also takes place (7th and 9th day): the blastocyst attaches itself to the uterine wall where it grows. Some structures form.
24
Q

Structures formed during implantation: Pericarp

A

trophoblast multiples rapidly to form pericarp.
- protection layer

25
Q

Structures formed during implantation: Amniotic fluid

A

The fluid protects the organism from impact, regulates temperatures, and provides a weightless environment that facilitates movement.

26
Q

Structures formed during implantation: Yolk sac

A
  • Produces blood cells until the liver, spleen, and bone marrow are mature enough to take over.
27
Q

Structures formed during implantation: Chorion

A
  • Protective membrane through which the placenta forms.
  • It contains small blood cells that adhere to the uterine wall.
28
Q

Structures formed during implantation: Placenta

A
  • Ensures transfer of nutrition and oxygen to the organism and takes care of waste removal.
  • Forms a membrane through which the substances can be exchanged without the blood of the mother and the child mixing.
29
Q

Structures formed during implantation: Umbilical cord

A
  • The connection between the placenta and the organism.
  • It contains one large vein that delivers blood with nutrients.
  • It also contains two arteries that carry away waste products.
30
Q

Period of the Embryo

A
  • Between 3rd and 8th weeks after fertilization.
  • Rapid prenatal changes take place
  • Groundwork for internal organs and body structures.
  • The supporting systems, such as the amnion, umbilical cord, and placenta, as well as the organs continue to develop.
  • The embryo is now very sensitive to changes in the environment.
  • In the last half of the first month, the embryonic disk forms three layers of cells.
    1. The ectoderm: the nervous system and skin
    - Forms a neural tube that begins to swell to form the brain at around 3.5 weeks.
    2. The mesoderm: the muscles, bones, circulatory system, and other internal organs.
    3. The endoderm: the digestive system, lungs, urinary tract, and glands.
  • During the second month, eyes, ears, nose, jaw, and neck are formed. Arms, legs, fingers, and toes as well. The intestines grow, as well as the liver and spleen.
31
Q

Period of the fetus

A
  • From the 3rd month to birth
  • Organs, muscles, and the nervous system begin to organize and become connected.
  • Foetus can move.
  • Genitals can be identified.
  • During the second trimester, the mother can experience movement.
  • Brain weight increases rapidly.
  • During the third trimester, the fetus reached the age of viability.
  • Fetus received antibodies from the mother.
32
Q

Sensitive periods of the fetus

A
  1. Central nervous system = whole time
  2. Heart = 3.5-9 weeks
  3. Arms = 4-9 weeks
  4. Eyes = 4.5 onwards
  5. Legs = 4-9 weeks
  6. Teeth = 7-16 weeks
  7. Palate = 7-10 weeks
  8. External genitalia= 7.5 onwards
  9. Ears = 4-20 weeks
33
Q

Teratogens

A

Environmental factors

34
Q

Effects of teratogens

A
  • During critical periods of development.
  • Specific effects on specific organs.
  • Genotype might counteract its effect. Vulnerability!
  • The effect of one can intensify the effects of another.
  • Different teratogens produce the same defect.
  • The longer the exposure, the higher the intensity of the effect
  • Sleeper effect: damage appears later in life.
35
Q

Legal and Illegal drug effects: Caffeine

A

Low birth weight, poor IQ and poor motor control, high risk miscarriage

36
Q

Legal and Illegal drug effects: Alcohol

A
  • 6% of births for alcoholic mothers.
  • Foetal alcohol syndrome (FAS): a lot of drinking, affects the heart, limbs, face, learning, IQ, ADHD link
37
Q

Legal and Illegal drug effects: Nicotine

A
  • ADHD link, low birth weight, genetic damage, cognitive and social development damage, and respiratory diseases.
38
Q

Legal and Illegal drug effects: Marijuana

A

Affect growth, low birth weight, genetic damage, cognitive, and social development damage, and respiratory diseases.

39
Q

Legal and Illegal drug effects: Cocaine

A

Physical and behavioral problems, neural damage, long-term effects

40
Q

Legal and Illegal drug effects: Aspirin/diet pills

A

Affect fetus > low birth weight, IQ and motor control

41
Q

Environmental toxins + parents’ factors

A
  • Pollution, pesticides, radiation, mercury, food additives, cosmetics, lead, etc.
  • Father’s exposure to these also affects the child (genetically).
  • Age, diet, disorders.