Brainscape's Knowledge GenomeTM

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


See full index

Biology Subject Test (SAT II) > Chapter Six: Classical Genetics > Flashcards

Chapter Six: Classical Genetics Flashcards

1
Q

Who is the father of modern genetics?

A

Gregor Mendel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How did Mendel study inheritance?

A

He bred garden peas and collected data from hundreds of plants across many generations and applied statistical analysis to his data

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What 3 laws did Mendel’s work establish?

A

Law of dominance
Law of segregation
Law of independent assortment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is probability?

A

The likelihood that a particular event will happen. It cannot predict whether it will actually occur, but if the sample is large enough it can give an average outcome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

State the law of dominance

A

When two organisms, homozygous (pure) for two opposing traits are crossed, the offspring will be hybrid (carry two different alleles) but will only exhibit the dominant trait.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

State the law of segregation

A

During the formation of gametes, the two traits carried by each parent separate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a monohybrid cross?

A

Cross between two organisms that are hybrid for a single trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the phenotype (what it looks like) ratios from a monohybrid cross?

A

75% dominant trait

25% recessive trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the genotype ratio for a monohybrid cross?

A

25% homozygous dominant
50% heterozygous
25% homozygous recessive

1:2:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

If the offspring phenotype ratio is 3:1 what were the parents?

A

They both were hybrid for the trait (monohybrid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a test/back cross

A

Is a way to determine whether an individual organism showing the dominant trait is is homozygous dominant or heterozygous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is a test cross done?

A

The individual is crossed with a homozygous recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain the 2 outcomes of a test cross

A
  • If the individual was homozygous dominant all offspring will have hybrid genotype (dominant)
  • If the individual was hybrid 50% or at least one of the offspring will show the recessive trait
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a gene, and what is an allele?

A

Gene specifies which trait, allele specifies what form the gene takes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

State the law of independent assortment

A

During gamete formation when 2 hybrids for 2 traits on separate chromosomes are crossed, the genes for 1 trait are not inherited along with the genes for another.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is incomplete dominance?

A

It is characterised by blending but one, allele is more noticeable than the other. Unlike in Co dominance where both are expressed equally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are alleles written incomplete dominance?

A

Different letters, all capitals since neither trait is dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is co dominance?

A

When both traits are fully expressed. (the genotype has both dominant traits)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Most genes in a population often exist in 2 allelic forms. When > 2 its called:

A

Multiple alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Humans have 4 blood types. How many different alleles?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How are homozygous A and hybrid A written? Also state in terms of I

A 
AA= I^A
A(O)= Ai
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is blood type O written?

A

It is recessive

(ii)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are characteristics controlled by many genes (by blending) called?

A

Polygenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Which factor determines how alleles are inherited?

A

How the homologous pairs line up on the Metaphase plate during Metaphase 1 of meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is a dihybrid cross?

A

Cross between individuals that are hybrid for two different traits (Tt Yy × To Yy)

26
Q

What are phenotype ratios for a dihybrid cross?

A

9:3:3:1

recall punnet square for Tt Yy

27
Q

What are traits/genes carried on X chromosome called?

A

Sex-linked

28
Q

Why is it that males suffer sex-linked conditions more than females?

A

If the condition is due to recessive mutation the female can express it only if she inherits 2 mutated genes, if one she’s only a carrier. If a male carries one mutated X-linked gene he will express it

29
Q

2 examples of common recessive sex-linked traits are:

A

Color blindness

Hemophilia

30
Q

In sex-linked inheritance how are daughters and sons affected from parents?

A

Affected (they have to express cannot be carriers, mutated X) fathers pass traits to daughters(carriers)
Fathers cannot pass it on to sons because they only pass on the Y chromosome
Carriers mothers can pass on the trait to sons (50% chance)
Daughters can be affected only if both parents have the trait (2 mutated Xs)

31
Q

Apart from genetic predisposition what can alter the expression of genes?

A

The environment

32
Q

Inheritance can be influenced by sex. What does this mean?

A

This means that a particular traits genotype and phenotype and differ between genders

33
Q

What is a karyotype

A

It is a laboratory procedure that analyses the size, shape and number of chromosomes

34
Q

How is a karyotype done?

A

Chromosomes are prepared and photographs during metaphase of mitosis

35
Q

Differentiate the 2 types of the 46 chromosomes

A 
44 autosomes (22 pairs) 
2 sex chromosomes (1 pair)
36
Q

What is a pedigree and how does it work?

A 
It is a family tree uses to study how a phenotype of a trait is inherited for every member of a family. 
Females=circle
Males=sqaure
Carrier=half shaded (not often shown) 
Affected=full shaded
37
Q

Recall autosomal dominant, autosomal recessive, sex linked dominant, sex linked recessive traits

38
Q

What is a mutation?

A

Abnormalilty in the genome

39
Q

What is a gene mutation?

A

Caused by a change in DNA sequence

40
Q

What is a chromosome mutation?

A

A chromosome may sustain an addition or deletion, or a cell may even have a new chromosome, which results from nondisjunction

41
Q

What are homologous chromosomes?

A

A couple ofhomologs are a set of 1 maternal and 1 paternalchromosomethat pair up duringfertilization. Homologs have the samegenesin the samelociwhere they provide points along each chromosome which enable a pair of chromosomes to align correctly before separating during meiosis

42
Q

What is nondisjunction?

A

An error that sometimes happen during meiosis in which homologous chromosomes fail to separate

43
Q

How can nondisjunction affect a zygote?

A

When nondisjunction happens 1 gamete received 2 homologues while the other receives none. When one of these gametes are paired with a normal gamete the zygote chromosome number is abnormal

44
Q

What is an abnormal chromosome condition called?

A

Aneuploidy

45
Q

What is a condition called when chromosome is present in triplicate?

46
Q

An organism with cells with an extra set of chromosomes is called?

A

A triploid (3n)

47
Q

An organism with more than 3 sets of chromosomes?

48
Q

What is deletion?

A

A fragment lacking a centromere is lost during cell division

49
Q

What is inversion?

A

A chromosomal fragment reattaches to it’s original chromosome but in the reverse orientation

50
Q

Which mutations are visible under microscope

A

Chromosomal

51
Q

What is translocation (in terms of chromosomal aberrations)

A

A fragment of a chromosome becomes attached to a non homologous chromosome

52
Q

What is polyploidy?

A

Having extra sets of chromosomes

53
Q

State what type of disorder Phenylketonuria is, it’s pattern of inheritance, and describe it

A
  • genetic
  • autosomal recessive
  • inability to break down the amino acid phenylalanine. Intake of it in diet results in mental retardation
54
Q

State what type of disorder Cystic Fibrosis is, it’s pattern of inheritance, and describe it

A
  • genetic
  • autosomal recessive
  • buildup of extracellular fluid in the lungs, digestive tract etc
55
Q

State what type of disorder Tay-Sachs disease is, it’s pattern of inheritance, and describe it

A
  • genetic
  • autosomal recessive
  • onset in early life, caused by lack of enzyme to break down lipids essential for normal brain function, seizures blindness and early death
56
Q

State what type of disorder Huntingtons disease is, it’s pattern of inheritance, and describe it

A
  • genetic
  • autosomal dominant
  • onset in middle age, disease of the nervous system, certain early death
57
Q

State what type of disorder Hemophilia is, it’s pattern of inheritance, and describe it

A
  • genetic
  • sex-linked recessive
  • caused by the absence of 1/more proteins necessary for normal blood clotting
58
Q

State what type of disorder Color blindness is, it’s pattern of inheritance, and describe it

A
  • genetic
  • sex-linked recessive
  • being red-green colourblind is rarely more than inconvenience
59
Q

State what type of disorder Downs syndrome is, it’s pattern of inheritance, and describe it

A
  • chromosomal
  • 47 chromosomes with trisomy-21 = an extra #21 chromosome
  • characteristic facial features, mental retardation, prone to developing Alzheimer’s and leukaemia
60
Q

State what type of disorder Klinefelters syndrome is, it’s pattern of inheritance, and describe it

A
  • chromosomal
  • XXY 47 chromosomes = male with extra X chromosome
  • male genitals, but testes are abnormally small and men are sterile
61
Q

What are the genotypic ratios for the monohybrid cross?

A

1 Homozygous dominant: 2 Hybrid: 1 Homozygous recessive

62
Q

What are the phenotypic ratios for the monohybrid cross?

A

3 dominant: 1 recessive

Biology Subject Test (SAT II) (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions