Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MED 109- BIOLOGY II > 4. DEGREES OF DOMINANCE > Flashcards

4. DEGREES OF DOMINANCE Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q
  1. What are the three degrees of dominance?
A
  1. Complete Dominance
  2. Incomplete Dominance
  3. Co-dominance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q
  1. What is Complete Dominance?
A

THIS OCCURS WHEN:
- the phenotypes of the heterozygote are identical to
the phenotypes of the dominant homozygote
- the dominant allele is expressed in the phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q
  1. What is Incomplete Dominance?
A

THIS OCCURS WHEN:
- the phenotype of the heterozygous F1 Hybrid is
somewhere in between the phenotypes of the 2
parental phenotypes
- the phenotype is a mix of the 2 parental varieties
- neither parental phenotype is distinguishable
- neither allele is expressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
  1. What is the phenotype associated with Incomplete Dominance known as?
A
  • an Intermediate Phenotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q
  1. What is Co-dominance?
A
  • 2 dominant alleles affect the phenotype
  • they do this in distinguishable ways
  • the parental phenotypes are distinguishable
  • both alleles are expressed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  1. Provide 2 examples of Incomplete Dominance .
A
  1. PALOMINO HORSES
    - this is when a brown and a white horse mate
    - the offspring is beige in colour
  2. CARNATION FLOWERS
    - this is when a red and white flower are genetically
    crossed
    - the offspring are pink in colour

NB:
- the offspring are heterozygous
- they have an intermediate phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
  1. Provide an example of Co-dominance?
A

HUMAN BLOOD GROUP TYPES:
- these consist of 3 alleles
- Blood Group A are dominant alleles
- Blood Group B are dominant alleles
- Blood Group O are recessive alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  1. Why are Blood Group A and B considered dominant alleles?
A
  • they have carbohydrates on the surface membrane of the red blood cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  1. Why is Blood Group O considered recessive?
A
  • there is no carbohydrate present on the surface membrane of the red blood cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
  1. What happens when we have an AA or AO Blood Group Genotype?
A
  • the phenotype is Blood Group A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. What happens when we have an BB or BO Blood Group Genotype?
A
  • the phenotype is Blood Group B
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
  1. What happens when we have an OO Blood Group Genotype?
A
  • the phenotype is Blood Group O
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  1. What happens when we have an AB Blood Group Genotype?
A
  • the phenotype is Blood Group AB
  • both alleles are dominant
  • the alleles are co-dominant
  • both alleles are expressed in the phenotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  1. How do most genes exist in populations?
A
  • most genes exist in more than 2 allelic forms

EG: human blood group types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  1. What are the 4 phenotypes of the ABO blood group
    (A, B, AB, O) in humans determined by?
A

THEY ARE DETERMINED BY:
- three alleles
- these alleles exist for the enzyme (I)
- this enzyme attached A or B carbohydrates to red
blood cells
(IA, IB, IO/i)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q
  1. Which enzyme adds the A carbohydrate to the red blood cells?
A
  • the enzyme encoded by the IA allele
17
Q
  1. Which enzyme adds the B carbohydrate to the red blood cells?
A
  • the enzyme encoded by the IB allele
18
Q
  1. Which enzyme adds neither A or B carbohydrates to the red blood cells?
A
  • the enzyme encoded by the i (IO) allele
19
Q
  1. Do alleles interact?
    What does this result in?
A
  • NO
  • this means that a dominant allele does not subdue a
    recessive allele
20
Q
  1. What are alleles variations in?
A
  • they are variations in a gene’s nucleotide sequence
21
Q
  1. What does the relationships of dominant and recessive alleles depend on for any character?
A
  • it depends on the level at which we examine the
    phenotype
22
Q
  1. Are dominant alleles more common in populations than recessive alleles?
A
  • no
23
Q
  1. Provide an example of a recessive allele that is more common than a dominant allele.
A

THE RECESSIVE ALLELE FOR 5 FINGERS/TOES:
- this is more common
- the dominant allele is for 6 fingers
- this is less common

NB:
- 1 out of every 400 babies in the US is born with extra
toes or fingers

24
Q
  1. What is Pleiotropy?
A
  • this is the property that most genes have
  • it allows them to have multiple phenotypic effects
25
Q
  1. Provide an example of Pleiotropic alleles?
A
  • Pleiotropic alleles are responsible for the multiple
    symptoms of certain hereditary diseases
  • EG: Cystic Fibrosis
    : Sickle- Cell Disease
26
Q
  1. What are some traits controlled by?
A
  • they are controlled by 2 or more genes
27
Q
  1. What are 2 examples of traits that are controlled by
    2 or more genes?
A
  1. Epistasis
  2. Polygenic Inheritance
28
Q
  1. What is Epistasis?
A
  • this is a phenomenon where the effects of 1 gene are
    modified by 1 or several other genes
  • this is when a gene at one locus alters the phenotypic
    expression of a gene at a second locus
29
Q
  1. What is Polygenic Inheritance?
A
  • this is the reverse of Pleiotropy
  • this is when 2 or more genes control the expression of
    a single phenotype
  • they have additive effects
  • this means that the phenotype expresses the sum of
    the effects of the numerous genes
30
Q
  1. What is the result of Epistasis?
A
  • 2 different gene sets affect the same phenotypic
    characteristic
31
Q
  1. Provide an example of Epistasis in animals?
A
  • their coat colour
  • it depends on two genes

ONE GENE:
- determines the pigment colour
- the allele B is for black
- the allele b is for brown

THE SECOND GENE:
- determines whether the pigment will be deposited
into the hair
- the allele C is for colour
- the allele c is for no colour

32
Q
  1. Provide an example of Epistasis in humans?
A
  • Albinism
33
Q
  1. What is Albinism?
A
  • this is a congenital autosomal recessive disorder

IT IS CHARACTERISED BY:
- a complete or partial absence of pigment
in the skin, hair and eyes

34
Q
  1. What causes Albinism?
A
  • it is caused by an absence or defect of Tyrosinase
  • this is the enzyme responsible for the production of
    melanin
35
Q
  1. What happens when a person has an albinism allele?
A
  • this allele will inhibit the expression of specific genes
  • these genes are responsible for hair and eye colour
36
Q
  1. What is Polygenic Inheritance usually characterised by?
A
  • it is usually characterised by quantitative variation
37
Q
  1. Provide a definition of Quantitative Characters?
A
  • these are the characters that vary in population
  • they vary along a continuous variation
  • this is known as a Continuum
38
Q
  1. What is an example of Polygenic Inheritance?
A
  • height
  • skin colour

MED 109- BIOLOGY II (90 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions