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CU: Genetics > Chapter 2: Heredity > Flashcards

Chapter 2: Heredity Flashcards

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Biology 101 flashcards
1
Q

What about God’s authority in heredity?

A
  • It shows that God is detailed and knows everything (heredity has detailed interactions at cellular level)
  • As Stewards we must manage well the information that has been given to us
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2
Q

Who was Gregor Mendel?

A
  • The Man who discovered the basics of Genetics
  • Main studies in 1856-1873
  • first scientist to combine data in a collection, analyze and provide an explanation theory to understand heredity
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3
Q

What are genes? What do they do?

A

The basic unit of heredity, a section on the DNA code of a chromosome for a protein that is often associated with a trait
Do: underly formation of heritable traits, some from one gene, some from multiple

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4
Q

What is heredity?

A

how genes get transmitted from parents to offspring

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5
Q

What is the background of Mendel’s work? (first techniques, questions, theories)

A
  • Artificial (human) selection is the first applied genetic technique
  • Results were unpredictable
  • Abbot Napp (1837): what is inherited? how? what is the role of chance? (Napp presided over Mendel’s monastery at time of experiments)
  • Misleading theories: Homunculus: only one parents contributes or Blended inheritance: traits mixed and changed in offspring
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6
Q

Artificial selection

A
  • to control mating by choosing the next generation’s parents
  • Domestication of plants/animals goes with the advancement of civilization
  • Adam and children undoubtedly practiced this because they were intelligent
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7
Q

What did Mendel’s laws do and what were his keys to success?

A

Laws: allow predictions for when traits appear, disappear, and reappear
Keys: - pure-breeding line of peas that bred by cross-fertilization and selfing, grew quickly, and constant traits
- Inheritance of alternative forms of traits were antagonistic
- He was brilliant with carefully planned and carried out, crossed, and analyze

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8
Q

What were the antagonistic pairs of traits Mendel studies?

A

(7) Seed color, seed shape, flower color, flower position, pod color, pod shape, and stem length

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9
Q

What does the monohybrid crosses reveal?

A

The unit of inheritance and the law of segregation
- Cross pure-breeding lines differs in one trait
- Both plant parents have two copied of inheritance unit with two forms, if it is in the F1 it is dominant if it is not it is recessive

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10
Q

What is seen in the phenotype of F1 and F2?

A

F1: progeny only one of parental traits
F2: both parental traits reappear in 3:1 ratio
**Disproves both prior theories
- results form reciprocal crosses produced similar results

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11
Q

What are alleles?

A

Different forms of genes

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12
Q

What is the difference between phenotype and genotype?

A

Observable characteristics and a pair of alleles

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13
Q

What is the difference between homozygote and heterozygote?

A

Homo: same alleles
Hetero: different alleles

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14
Q

What is the law of segregation?

A

two alleles separate during gamete formation and two gametes unite at fertilization
- F1: two kinds of gametes 1:1
- F2 3:1 ratio, 1/4 dom, 1/2 hybrid, 1/4 reces
- Verified by further croses
F2 selfed to F3 gets alll green from pure breeding, 1/3 yellow from pure breeding, 2/3 yellow from hybrid

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15
Q

What is the product rule?

A

Probability of two independent events occurring together is the product of the individual probabilities
Yy, Yy, get YY is 1/4

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16
Q

What is the sum rule?

A

probability of either of two mutually exclusive events occurring is the sum of individual probabilities
Yy x Yy get Uu is 1/4 + 1/4 = 1/2

17
Q

What do test crosses do?

A

Reveal unknown genotype: dominant homo or hetero?

18
Q

What genotypes and phenotypes will a cross of two heterozygous parents create?

A

3:1 phenotype
3 genotypes
- self-breeding has a push toward homozygosity

19
Q

What is independent assortment? What reveals it?

A
  • During gamete formation different pairs of alleles segregate independently
  • revealed by dihybrid cross
  • 9:3:3:1 phenotype
  • 4 gametes, 4 phenotypic classes, 2 parental type and two recombinant types (combination of parents)
20
Q

What are branching line diagrams?

A

Used for more complex gene crosses
- progeny phenotypes for each gene are show in different columns
- Gene 1: note fraction, Gene 2: note fractions, use product rule to get final fraction

21
Q

How do you predict offspring in complicated crosses?

A
  • # different gametes = 2^n
  • n = number of different traits
    (AaBbCcDd) = 2^4 = 16
    Multiply gamete numbers to determine number of total genotypes
    AaBbCcDd x AaBbCcDd = 2^4 x 2^4 = 256
  • Calculate probability of each gene then use product rule
    AaBbCcDd x AaBbCcDd probablitity = AAbbCcDd?
    Aa x Aa = AA 1/4
    Bb x Bb = bb 1/4
    Cc x Cc = Cc 1/2
    Dd x Dd = Dd 1/2
    1/4 x 1/4 x 1/2 x 1/2 = 1/64
22
Q

How did the science of genetics begin?

A
  • rediscovering Mendel’s work: early-mid 1800s, published 1860s
  • Darwin published right before Mendel
  • Late 1800s three labs similar conclusions to Mendel ~1905 take advantage to increase food production
  • labs lead by botanists from Germany, Denmark (Dutch), Austria
23
Q

What is the molecular explanation for the pea appearances?

A
  • R allele: encodes enzyme that makes Starch branch (Sbe 1)
  • r allele not make Sbe1 so has sucrose and unbranched starch causing shrinking and wrinkling
  • Y allele encodes enzyme (Sgr) breaks down chlorophyll
  • y allele not make Sgr so Chlorophyll not broken down (stay green)
24
Q

What are the two general molecular principles?

A
  • Specific gene determines specific enzyme whose activity may affect phenotype
  • Dominant normally functioning protein
  • Recessive alleles not encode functioning protein (from mutation or God-built in flexibility)
25
Q

What about Mendelian inheritance in humans?

A
  • many inheritable traits care caused by interactions of many genes do not show Mendelian inheritance patterns
  • single-gene traits in humans are also tricky when trying to determine inheritance: long generation time, small number progeny, no controlled mating, and no pure-breeding lines
  • some most common single-gene trait diseases caused by recessive alleles in humans
  • Use pedigrees
26
Q

What are the symbols in pedigrees?

A

Square - male, circle - female, diamond (unknown/unspecified)
shading: condition/disease
line through: deceased
numbers: progeny
double line: consanguineous mating (cousins)

27
Q

What about cystic fibrosis and genetics?

A
  • recessive allele, encoding abnormal CFTR protein that allows for passage of chloride ions across the membrane (absent in lung affecting breathing)
28
Q

What about recessive traits in pedigrees?

A
  1. Can have unaffected parents (heterozygous, “carriers)
  2. If both parents affected then all children should be affected
  3. Rare recessive traits: horizontal pattern of inheritance
  4. Extremely common recessive traits may show vertical pattern of inheritance
29
Q

Dominant traits in pedigrees

A
  1. Affected children have at lease one affected parent
  2. Vertical pattern of inheritance
  3. Un affected children possible if both parents heterozygous

CU: Genetics (5 decks)

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