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Genetics > Lecture--Chapter 3 > Flashcards

Lecture--Chapter 3 Flashcards

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Biology 101 flashcards
1
Q

Hippocrates (~400 B.C.E.) proposed which idea?

A

pangenesis

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2
Q

J. Koelreuter (~1766) proposed:

A

blending hypothesis of inheritance

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3
Q

G. Mendel (1822-1884):

A
  1. Austrian monk
  2. Studied outcomes of thousands of crosses of pea plants
  3. father of genetics
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4
Q

What were the advantages of working with pea plants?

A
  1. Small, easily grown, form multiple seeds
  2. Each flower has male and female parts
  3. Many pea varieties were available with different characteristics such as: flower colour, plant height, appearance of pods and seeds
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5
Q

Define self-fertilisation (or selfing):

A

A pea plant can fertilise itself.

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6
Q

Define cross-fertilisation (or crossing):

A

One pea plant can be used to fertilise a different pea plant.

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7
Q

Pea flowers produce:

A
  1. pollen (sperm)
  2. eggs
  3. a central cell

The keel petal encloses both male and female organs.

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8
Q

Pollen grains form:

A

A pollen tube that transfers two sperm cells to the ovule. This produces a zygote (2n) and endosperm (3n).

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9
Q

What were the steps that Mendel took to cross-fertilise pea plants?

A
  1. remove anthers from purple flower
  2. transfer pollen from anthers of white flower to the stigma of a purple flower (parental generation)
  3. cross-pollinated flower produces seeds
  4. plant the seeds (yields first-generation offspring)
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10
Q

What were the 7 characters and their variants that Mendel studied?

A
  1. height–tall, dwarf
  2. flower colour–purple, white
  3. flower position–axial, terminal
  4. seed colour–yellow, green
  5. seed shape–round, wrinkled
  6. pod colour–green, yellow
  7. pod shape–smooth, constricted
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11
Q

F1 generation is produced by:

A

cross-fertilisation

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12
Q

F2 generation is produced by:

A

self-fertilisation

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13
Q

Define the particulate theory of inheritance:

A

hereditary factors are discrete

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14
Q

During gamete formation:

A

the paired factors segregate randomly; each gamete has one factor

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15
Q

Define Mendel’s Law of Segregation:

A

the two copies of a gene segregate from each other during transmission from parent to offspring

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16
Q

Reginald Punnett:

A

proposed a method for predicting results of a genetic cross (using a Punnett square)

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17
Q

What is the 5 step process of predicting results of a genetic cross?

A
  1. Write down the genotypes of both parents.
  2. Write down the possible gametes that each parent can make.
  3. Create an empty Punnett square; place the possible male gametes along the top, and female gametes along the side.
  4. Fill in the possible genotypes of the offspring by combining the alleles of the gametes in the empty boxes.
  5. Among the possible offspring, determine the relative proportion of genotypes and phenotypes.
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18
Q

Define genotype:

A

allele composition

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19
Q

Define phenotype:

A

observable traits

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20
Q

What are the two possible patterns of data from dihybrid crosses?

A

traits are either linked or unlinked

21
Q

What determines unlinked traits in dihybrid crosses?

A

The presence of non-parentals in the F2 (having combinations of traits not found in the true-breeding plants of the parental generation); suggests that the traits are unlinked and segregate independently.

22
Q

Mendel’s Law of Independent Assortment:

A
  1. Two different genes randomly assort their alleles during the formation of haploid cells.
  2. During gamete formation, the segregation of any pair of hereditary determinants is independent of the segregation of other pairs.
  3. Important consequence
23
Q

Define important consequence:

A

One individual can produce a very large number of different gametes.

24
Q

Define loss of function alleles:

A

Gene mutations that result in a defective or absent product.

a. May reveal information about the gene’s function.
b. One of the most common types of genetic mutation studied.
c. By chance, Mendel’s 7 chosen traits involved loss-of-function alleles.

25
Q

What happened in 1866?

A

Gregor Mendel analysed the transmission of traits from parents to offspring and showed that it follows a pattern of segregation and independent assortment.

26
Q

What happened in 1876-1877?

A

Oscar Herwig and Hermann Fol observed that the nucleus of the sperm enters the egg during animal cell fertilisation.

27
Q

What happened in 1883?

A
  1. Wilhelm Roux proposed that the most important event of mitosis is the equal partitioning of “nuclear qualities” to the daughter cells.
  2. Edouard van Beneden showed that gametes contain half the number of chromosomes and that fertilisation restores the normal diploid number.
28
Q

What happened in 1884-1885?

A

Hertwig, Strasburger and August Weismann proposed that chromosomes are carriers of the genetic material.

29
Q

Define the chromosome theory of inheritance:

A

inheritance patterns of traits can be explained by transmission patterns of chromosomes

30
Q

Chromosome theory of inheritance:

A
  1. Chromosomes contain the genetic material that is transmitted.
  2. Chromosomes are replicated and passed from parent to offspring.
  3. The nuclei of most eukaryotic cells contain chromosomes that are found in homologous pairs.
  4. During the formation of gametes, different types of nonhomologous chromosomes segregate independently.
  5. Each parent contributes one set of chromosomes to its offspring.
31
Q

During segregation of homologs during meiosis:

A

The 2 copies of a gene segregate from each other during transmission from parent to offspring.

32
Q

Laws of inheritance can be used to predict the possible results of genetic crosses:

A
  1. animal and plant breeding

2. predicting the likelihood of an affected child in families with a known genetic disease

33
Q

Define probability:

A

The probability of an event is the chance that the event will occur in the future.
Probability = (# times event occurs) / (total # events)

34
Q

Define random sampling error:

A

the deviation between observed and expected outcomes

35
Q

What are the two methods to determine probability?

A
  1. Punnett Square

2. Forked Line Method (multiplication method)

36
Q

What does the forked line method entail?

A

independently calculates the probability of each trait

37
Q

What are the two event probability mathematical operations?

A
  1. sum rule

2. product rule

38
Q

What is the sum rule used for?

A

predicting mutually exclusive (either/or) events

39
Q

What is the product rule used for?

A

predicting two or more independent events (all)

40
Q

Sum rule:

A

Probability = the sum of their respective probabilities

ex. probability of either A or B = (probability of A) + (probability of B)

41
Q

Product rule:

A

Probability = product of their respective probabilities

ex. Probability of both A and B = (probability of A) x (probability of B)

42
Q

Hypothesis testing and the Chi Square Test:

A
  1. commonly used to determine whether genetic data supports a specific pattern of inheritance
  2. a statistical test for how well the data support the hypothesis
    a. evaluates the goodness of fit (not proof)
    b. accepts or rejects the hypothesis
43
Q

What is the formula for the Chi Square Test?

A

x^2 = (the sum){[(O - E)^2] / E}

44
Q

In the Chi Square Test formula, what does each variable represent?

A
  1. (the Greek E symbol) = sum of the calculations for each category
  2. O = observed data in each category
  3. E = expected number in each category based on the experimenter’s hypothesis
45
Q

In the Chi Square Test, the hypothesis:

A

provides the Expected values

46
Q

In the Chi Square Test, the data:

A

provides the Observed values

47
Q

In the Chi Square Test, the calculated c^2 value:

A

by itself is meaningless; it is interpreted using the P (probability) Value on a Chi Square values table.

48
Q

In the Chi Square Test, the degrees of freedom:

A

the number of possible outcomes (n) provides the degrees of freedom:
degrees of freedom = n - 1

Genetics (18 decks)

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