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Chromosomes and genes > Lecture 7 and 8 > Flashcards

Lecture 7 and 8 Flashcards

1
Q

What is the theory of pangensis?

A

Seeds are produced by all body parts, collected in reproductive organs and transmitted to offspring

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2
Q

Who proposed the theory of pangenesis?

A

Hippocrates (400B.C.)

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3
Q

What is the theory of preformationism?

A

Sex cells contain fully developed homunculus (mini human)

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4
Q

What were the two theories surrounding preformationism?

A

Spermists: homunculus found in sperm
Ovists: homunculus resides in egg

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5
Q

What is the blending theory of inheritence?

A

Hereditary traits are malleable, blending together through generations

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6
Q

What plant did Mendel work with?

A

Peas: Pisum satvium

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7
Q

Why peas?

A

Easy to handle, grow well, self fertilise or cross fertilise, short generation time, lots of offspring, discrete traits, pure bred strains exist

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8
Q

What were the basic ratios in Mendel’s experiments:

A

F1: all the same
F2: 3:1 ratio

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9
Q

What did Mendel’s data suggest?

A

Particulate theory of inheritance

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10
Q

What is Mendel’s first law?

A

Law of segregation

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11
Q

What is the law of segregation?

A

Two factors for each trait separate during gamete formation and unite at random at fertilization

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12
Q

What was Mendel’s experiments involving more then one phenotype called?

A

Dihybrid cross

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13
Q

What is Mendel’s second law?

A

The law of independent assortment

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14
Q

What is the law of independent assortment?

A

During gamete formation, different pairs of alleles segregate independently of each other

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15
Q

What enzyme causes wrinkled peas?

A

Starch branching enzyme 1 (Sbe1)

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16
Q

What enzyme causes green phenotype?

A

Lack of an enzyme that breaks down Chlorophyll called stay green (Sgr)

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17
Q

How are family genetics analysed?

A

Pedigree analysis

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18
Q

What are 2 features of dominant diseases?

A
  • Affected individuals have affected parent

- Doesn’t skip generations

19
Q

Give an example of a dominant disease in humans.

A

Huntington’s disease (progressive death of nerve cells)

20
Q

What is the inheritence of dominant disease also called?

A

Vertical transmission

21
Q

What is the mechanism for huntingtons?

A

Httex1 gene variant produces abnormally folded proteins

22
Q

Why do misfolded Httex1 genes cause huntingtons?

A

Protein accumulates in neurons causing damage over time

23
Q

What are features of recessive diseases?

A

Affected indivduals parents not always affected (skips generations)
Seen more in consanguineous matings

24
Q

Give an example of recessive disease in humans.

A

Cystic fibrosis

25
Q

What type of transmission are recessive disease?

A

Horizontal

26
Q

What is the most common non-functional varient of CFTR?

A

delta F508 (deleted amino acid at position 508)

27
Q

Snapdragons show variance from Mendel’s first law because…

A

Incomplete dominance: F2 gives 1:2:1 red:pink:white

28
Q

Lentils giving rise to spotted/dotted phenotype not seen in F1 generation is known as…

A

Co-dominance

29
Q

How many genotypes and phenotypes are there for blood groups?

A

6 and 4

30
Q

Why are blood groups this way?

A

More than one allele at a locus

31
Q

Why do dominance series exist?

A

There are dominance heirachys

32
Q

Give an example of a dominance series in mammals.

A

Agouti locus: Coat colour in mouse, wild type allele produces fur with yellow and black bands

33
Q

One gene can act on multiple systems or tissues. This is called…

A

Pleiotrophy

34
Q

Give an example of pleiotriophy in mice.

A

One Ay locus produces yellow coat colour,

Two Ay are not born (genotype is lethal)

35
Q

What is epistasis?

A

The interaction of genes that are not alleles (e.g. supression of the effect of one such gene by another)

36
Q

What are two key concepts when considering environment interactions of genes?

A

Penetrance and expressivity

37
Q

What is penetrance?

A

Proportion of a population with a genotype that have the phenotype

38
Q

What is expressivity?

A

The degree or intensity with which a particular genotype is expressed in a phenotype

39
Q

Give an example of expressivity

A

Siamese cats (same genotype, fur colour different), temperature sensitive gene for melanin

40
Q

Give an example of penetrance.

A

Phenylketonuria (PKU)

41
Q

What is phenylketonuria?

A

Recessive disease, mutation in phenlyalanine hydroylase, unable to metabolose phenylalanine which becomes toxic

42
Q

Why is phenlyketonuria an example of penetrance?

A

Phenotype changes depending on diet

43
Q

Who first demonstrated polygenetic inheritance?

A

Karl Pearson (1903), height is correlated in families

Chromosomes and genes (10 decks)

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