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Bio 120 Lab > Lab 5 & 6 > Flashcards

Lab 5 & 6 Flashcards

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Biology 101 flashcards
1
Q

Define Gene

A

A factor of inheritance for a particular trait or characteristic.
- Passed on from your parents to you

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2
Q

What is a gene composed of?

A

A specific nucleotide sequence in the DNA

- which acts as a template for RNA synthesis and ultimately the formation of a specific protein in a cell

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3
Q

A gene can come in different forms called ______

A

alleles

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4
Q

What is the difference between a gene and alleles?

A

Gene -seed color

Allele - green, yellow

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5
Q

Define Dominant allele

A

One whose phenotypic effect is the same in both the heterozygous and homozygous conditions

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6
Q

Define Recessive allele

A

One that is not expressed phenotypically in the heterozygous condition

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7
Q

Define Heterozygous

A

If it has two different alleles for the gene

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8
Q

Define Homozygous

A

If it has two identical alleles for the gene

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9
Q

Define Genotype

A

The genetic makeup of an organism

  • always use letters
  • Rr or GgHH
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10
Q

Define Phenotype

A

Expressed traits of an organism

  • use descriptive words (physical appearance)
  • purple seeds
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11
Q

Define Frequency

A

The proportion of one type of thing to the total population.
- range between 0 and 1

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12
Q

Give an example of a genotypic and phenotypic frequency

A

Genotypic frequencies - .5 Dd, .25 DD, .25 dd

Phenotypic frequencies - .75 green seeds, .25 white seeds

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13
Q

Define Ratio

A

The proportion of one type of thing to another

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14
Q

Give an example of a genotypic and phenotypic ratio

A

Genotypic ratio - 1 DD: 2 Dd: 1 dd

Phenotypic ration - 3 green seeds: 1 white seed

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15
Q

What is a Punnett square used for?

A

To stimulate the combinations of male and female gametes to form diploid zygotes (offspring)

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16
Q

Define a monohybrid cross

A

A cross between two organisms that differ with respect to one characteristic
- ex plant height

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17
Q

What is the principle of dominance ? (according to Mendel)

A

When parents differ in one characteristic, their hybrid offspring resemble only one of the parents, and are not a blend of the two parent phenotypes.

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18
Q

What is the principle of segregation? (according to Mendel)

A

Producing two kinds of reproductive cells
- half passing on the dominant character of one parent, and the other half passing on the recessive character of the other parent

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19
Q

What is Mendel’s first law?

A

Alleles of one gene segregate from one another during the formation of gametes
- monohybrid cross

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20
Q

Define Homologous

A

Chromosomes that carry the same genes at the same locations although the particular forms may be different.

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21
Q

The behavior of chromosomes during ______ account for Mendel’s 1st law ______

A

meiosis

The principle of segregation

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22
Q

The Mechanism of Segregation of Alleles during Gamete Formation
For a chromosome, in Prophase I with the genotype Tt:
- How many chromosomes would you need to draw for this stage?
- Are these chromosomes single of duplicated?

A
  • 2
  • duplicated
    TTtt
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23
Q

Define a dihybrid cross

A

A cross between two organisms that differ with respect to two characteristics
- EX. plant height & plant color

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24
Q

Monohybrid cross between T&t:

  • P1 tall plant genotype =
  • P2 dwarf plant genotype =
  • Genotype of P1 gametes =
  • Genotype of P2 gametes =
  • F1 generation genotype =
  • Genotypes of F1 gametes =
A
  • TT
  • tt
  • T
  • t
  • Tt
  • T & t
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25
Q 
Dihybrid cross:
 A plant that was homozygous for tall height and green color was crossed with a plant that was homozygous for dwarf size and albino color
Use T for height & G for color
- P1 tall & green plant genotype =
- P2 dwarf & albino plant genotype =
- Genotype of P1 gametes =
- Genotype of P2 gametes =
- F1 generation genotype =
- Genotypes of F1 gametes =
A
  • TTGG
  • ttgg
  • TG
  • tg
  • TtGg
  • TG, Tg, tG, tg
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26
Q

What are the predicted phenotypic frequencies for the F2 generation of this cross?

A

0.5625 tall & green, 0.1875 tall & albino, 0.1875 dwarf & green, 0.0625 dwarf & albino

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27
Q

What is Mendel’s 2nd law?

A

Alleles of different genes assort independently of one another during gamete formation
- dihybrid cross

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28
Q

The Mechanism of Independent Assortment of Alleles of Different Genes during Gamete Formation
For a chromosome in Prophase I with the genotype of F1 TtGg:
- How many chromosomes will you need to draw for this stage?
- Are these single or duplicated?

A
  • 4

- Duplicated

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29
Q

Define a Test Cross

A

Between a heterozygous individual and homozygous recessive individual (AaBb x aabb) to determine if genes are linked or not

30
Q

Which type of cross is used to determine if the genes are on the same or different chomosomes (gene linkage)?

A

Test cross

31
Q

Use the symbols A = seed color, B = texture:
- Heterozygous (red & smooth) =
- Genotype of gametes =
- Homozygous recessive (yellow & wrinkled) =
- Genotype of gametes =
Draw the test cross

A
  • AaBb
  • AB, Ab, aB, ab
  • aabb
  • ab
32
Q

Based on the previous test cross:

  • What is the predicted genotypic ratio?
  • What is the predicted phenotypic ratio?
A

1 AB: 1 Ab: 1 aB: 1 ab

.25 AB, .25 Ab, .25 aB, .25 ab

33
Q

Define Gene Linkage

How many gametes are formed?

A

Gene linkage is when the genes are linked together on the same chromosome
- only 2 gametes

34
Q

Define Chiasma formation

A

Chromosome breakage and reunion occurs at this stage

35
Q

Define crossing over

A

When genes are linked, the middle chromatids cross is late Prophase I and exchange 1 gene

36
Q

Define Recombinant type gametes

A

Ex. Ab or aB

Result due to the crossing over with gene linkage

37
Q

Define Sex chromosome

A

The morphology indicates whether an individual is male or female

38
Q

Define Autosomes

A

The remaining non-sex chromosomes in the nucleus

39
Q

What type of chromosomes do females have? Where are they located?

A

Females have two X chromosomes in the nucleus of every diploid cell

40
Q

What type of chromosomes do males have? Where are they located?

A

Males have one X and one Y chromosome in the nuclei of their diploid cells

41
Q
  • What will the gametes produced through meiosis in females contain?
  • What will the gametes produced by males contain?
A
  • They will contain a single X chromosome along with 22 autosomes
  • They will have either an X or Y chromosome plus the 22 autosomes
42
Q

The gender of any new offspring resulting from sexual reproduction is determined by what?

A

By the type of male gamete (X or Y) that fertilizes the female gamete (always X)

43
Q

Define Karyotype

A

The photographic representation of the chromosomes of an actively dividing cell, showing the number, shape and size of the chromosomes

44
Q

How is the karyotype for Turner Syndrome different from a normal female karyotype?
What are some phenotypic abnormalities?

A

It occurs when one of the two X chromosomes in WOMEN is missing

  • short stature, non-functioning ovaries (infertility)
  • also webbed neck
45
Q

How is the karyotype for Down Syndrome different from a normal karyotype?
What are some phenotypic abnormalities?

A

It is caused by an extra autosomal chromosome (#21)

- mild/moderate mental deficiency, almond shaped eyes, protruding tongue, poor muscle tone, shorter limbs + back

46
Q

How is the karyotype for Klinefelter Syndrome different from a normal male karyotype?
What are some phenotypic abnormalities?

A

It occurs when MEN have an extra X chromosome

- sterile with small testes, low levels of testosterone in their blood

47
Q

Define Mendelian fashion

A

Characteristics that appear to be inherited as dominant or recessive alleles of SINGLE genes

48
Q

Are the dominant phenotypic characteristics always the most common ones in the class?

A

No, most of the traits are in majority recessive, except for the tasting trait

49
Q

Genes located on the X chromosome are said to be _______

A

Sex-linked or X-linked genes

50
Q

What are some examples of phenotypes determined by sex-linked recessive genes?

A

Red-green color blindness
Total color blindness
Hemophilia

51
Q

Define Hemophilia

A

A genetic disease which is characterized by excessive bleeding (blood does not clot) following injury and is caused by a sex-linked recessive allele.

52
Q

Who is more likely to exhibit a sex-linked recessive trait? Why?

A

Males; because they only carry a single X chromosome… whereas women have two

53
Q

Would a Heterozygous female exhibit a sex-linked recessive trait?

A

A Heterozygous female would NOT exhibit a sex-linked recessive trait, but are ‘carriers’ of the trait

54
Q

Define Red-green color-blindness

A

General term for a spectrum of relatively common sex-linked recessive disorders

55
Q

What is a Protan deficiency?

A

Occurs is 2% of males and 0.04% of females

  • Caused by reduced amounts or complete absence of red photoreceptors in the eye
  • Results in reduced visibility of reds, along with darkening of reds
56
Q

What is a Deutan deficiency?

A

Occurs is 6% of males and 0.4% of females

  • Cause by reduced amounts of complete absence of green photoreceptors in the eye
  • Results in reduced visibility of greens
57
Q

What can result in a person having difficulty differentiating reds and greens? or distinguishing red and green shades?

A

Both Protan and Deutan deficiency

58
Q

Problems involving sex linkage:

  • A hemophiliac woman marries a normal man. (use H and h)
  • draw a Punnett square and predict the offsprings of this couple
A

All their sons would be hemophiliac
None of their daughters would have the condition, though they would be carries of it
LAB 6 - P.7

59
Q

Define Pedigree charts

A

The analysis of how phenotypic traits or genetic diseases are passed on from parents to offsprings
- sex-linked or autosomal traits(not sex-linked)

60
Q

What is the genotype of Queen Victoria of England?

What is the genotype of Alexis, son of the Tsar of Russia?

A
  • XHXH (normal female)

- XhY (affected male)

61
Q

How can you determine whether a trait is sex-linked or autosomal?

A 
Sex-linked = uses chromosomes XX and XY
Autosomal = uses letters
62
Q

In a pedigree chart, How can you determine if the allele is dominant or recessive?

A

Count
Black vs. white
Ex. More black diseased = disease is dominant

63
Q

Albinism is cause by what type of allele?

A

An autosomal recessive allele ‘a’

64
Q

The crossover frequency between two linked genes is proportional to what?

A

To the distance between them

65
Q

When is there a higher chance of crossover occurring?

A

If the two genes are farther apart, there is an increased probability of a crossover occurring during meiosis.. And therefore a higher proportion of recombinant gametes expected

66
Q

If recombinant types make up 18% of the test cross off springs, the two genes are considered to be ___ map units apart on the chromosome

A

18 map units apart

67
Q

What are recombinant gametes? And how can we identify them?

A

Recombinant gametes result from crossovers

We can identify them easily because they are produced in lower numbers than parental gametes in meiosis

68
Q

How can we calculate the percentage recombination?

A

It can be calculated by dividing the number of recombinants by the total number of offspring, and then multiplying by 100

69
Q

Polygenic traits

EX?

A

Show a continuous range of phenotypes in a population that approximates a normal distribution
EX. human height, skin pigmentation, IQ, production level of milk in cattle

70
Q

The effects of multiple alleles are ______

A

Additive

EX. skin pigmentation - a greater # of dominant alleles results in a darker skin pigment

71
Q

Dermatoglyphics

A

The pattern and number of epidermal ridges on the fingers (fingerprints)
- A polygenic trait

72
Q

What are the 3 types of epidermal ridges?

A

Arch, loop, whorl

Bio 120 Lab (4 decks)

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