Genetics Unit Test PPT. Flashcards
1
Q
study of genetics
A
- Study of how traits are passed from parent to offspring
- heredity
- inheritance
2
Q
Gregor Mendel
A
- Father of Genetics
- Mathematician
- Experimented with pea plant traits to follow inheritance
3
Q
What structures does the perfect flower have?
A
male and female structures
4
Q
anther
A
- male structure
- produces pollen containing sperm
5
Q
ovary
A
- female structure
- Produces ovules containing eggs
6
Q
Mendel’s Experiment
A
- Grew pure plants (P generation) that had 2 of the same alleles.
- Cross pollinated plants with contrasting traits to create F1 generation
- Cross two F1 tall plants to get the F2
7
Q
Law of Segregation
A
- During meiosis I homologous chromosomes separate.
- Offspring receives one gene for a trait from each parent.
8
Q
1N
A
haploid
9
Q
2N
A
diploid
10
Q
punnett square
A
- Used to predict the chances of offspring genotypes.
- Outcome is based on large number of offspring.
11
Q
Mendel’s Generations
A
- P generation
- F1 generation (Hybrid 4:0)
- F2 generation (3:1 ratio)
12
Q
Parental (P) generation
A
pure for a trait
13
Q
F2 generation
A
Offspring of F1
14
Q
Law of Independent Assortment
A
Inheritance of one trait has no effect on the inheritance of another trait when genes are on separate chromosomes
15
Q
What are traits determined by?
A
the genes on the chromosomes
16
Q
gene
A
a segment of DNA that determines a trait
17
Q
What do chromosomes come in?
A
homologous pairs
18
Q
What do genes come in?
A
pairs
19
Q
homologous pairs
A
matching genes – one from female parent and one from male parent
20
Q
Example of Homologous Pairs:
Humans have 46 chromosomes or 23 pairs.
A
One set from dad – 23 in sperm
One set from mom – 23 in egg
21
Q
alleles
A
different genes (possibilities) for the same trait – ex: blue eyes or brown eyes
22
Q
dominant allele
A
prevents the other allele from being expresses
23
Q
recessive allele
A
is NOT expressed even though it is present in the DNA
24
Q
symbol for dominant allele
A
upper case letter
25
symbol for recessive gene
lower case letter
26
How can a recessive trait be expressed?
Must have 2 recessive alleles for a recessive trait to be expressed
27
Always use the ____ letter for the same alleles.
same
28
Straight thumb is ______ to hitchhiker thumb
dominant
29
homozygous or purebred
Both genes of a pair are the same
ex.
TT – homozygous dominant
tt – homozygous recessive
30
heterozygous or hybrid
One dominant and one recessive gene
ex.
Tt – heterozygous
31
genotype
Combination of genes an organism has (actual gene makeup)
32
What is an example of a genotype?
Ex: TT, Tt, tt
33
phenotype
Physical appearance resulting from gene make-up
34
What is an example of a phenotype?
Ex: hitchhiker’s thumb or straight thumb
35
What does probability mean?
The chance of an event occurring
36
In order to get close to the predicted, what do you have to many of?
NEED MANY TRIALS
37
What is the punnett square based on?
many offspring (trials)
38
What is the punnett square used for?
Used to predict the possible gene makeup of offspring
39
karyotype
picture of an individual’s chromosomes
40
amniocentesis
amniotic fluid surrounding the embryo is removed for analysis
41
Dwarfism
variety of skeletal abnormalities
42
Huntington's Disease
gradual deterioration of brain tissue, shows up in middle age and is fatal
43
What are dominant gene mutations?
- dwarfism
| - huntington's disease
44
Phenylketonuria (PKU)
- an amino acid common in milk cannot be broken down and as it builds up it causes mental retardation
- newborns are tested for this
45
Cystic fibrosis
mucous builds up in the lungs
46
Tay-Sachs Disease
- deterioration of the nervous system
| - early death
47
What do mutated genes produce?
produce enzymes that are less effective than normal at breaking down fatty cell products known as gangliosides
48
What happens as result of what the mutated genes produced?
gangliosides build up in the lysosomes and overload cells. Their buildup ultimately causes damage to nerve cells
49
What are recessive gene mutations?
- sickle cell anemia
- Cystic fibrosis
- Tay-Sachs Disease
- Phenylketonuria
50
Sickle cell anemia
- red blood cells are sickle shaped instead of round and cannot carry enough oxygen to the body tissues
- heterozygous condition protects people from malaria
51
Gene or Point Mutation
- most common and least drastic
| - only one gene is altered
52
What does the inside of punnett squares represent?
possible offspring (2N)
53
What does the outside of the punnett square represent?
Male gametes - N (One gene in sperm) or
| Female gametes – N (One gene in egg)
54
What is the order to write a genotypic ratio?
homozygous dominant : heterozygous : homozygous recessive
55
What is the order to write a phenotypic ratio?
dominant : recessive
56
People have ___ chromosomes or ___ pairs.
- 46
| - 23
57
homologous
look alike
58
autosomes
determine body traits
59
22 pairs are _________.
homologous
60
What are the 22 homologous pairs called?
autosomes
61
1 pair is a ____ chromosome
sex
62
sex chromosomes
determines sex (male or female)
63
Female
- sex chromosomes are homologous (look alike)
| - label XX
64
Male
- sex chromosomes are different
| - label XY
65
What is the probability of a couple having a boy? Or a girl?
50/50 chance
66
incomplete dominance
When one allele is NOT completely dominant over another they produce a blended phenotype
67
What is an example of incomplete dominance?
In carnations the color red (R) is incompletely dominant over white (W). The hybrid color is pink.
68
codominance
When both alleles are expressed individually
69
What is an example of complete dominance?
- In certain chickens black feathers are codominant with white feathers.
- Heterozygous chickens have black and white speckled feathers.
70
ROAN Cow
Red allele: R
White allele: W
Roan: RW
71
Blood Type Alleles
Alleles for a protein on the Red Blood Cell
72
I^A
Alpha protein
73
I^B
Beta protein
74
i^o or i
neither
75
Possible Blood genotypes
- Type A
- Type B
- Type AB
- Type O
76
SRY
Sex determining Region of the Y
77
Sex-linked traits
Genes for these traits are located only on the X chromosome (NOT on the Y chromosome)
78
Why are x-linked alleles expressed in males whether dominant or recessive?
males have only one X chromosome
79
What are examples of recessive sex-linked disorders?
- colorblindness
| - hemophilia
80
colorblindness
inability to distinguish between certain colors
81
What is the most common type of color blindness?
red-green color blindness, where red and green are seen as the same color
82
hemophilia
blood won’t clot
83
Barr body
- In females one X chromosome is inactivated in each cell.
| - Some cells have one X turned off and some cells have the other X turned off.
84
Calico Cat color expression
X^B X^O
85
pedigree
Diagram of a trait passed through generations
86
circles =
females
87
squares =
males
88
horizontal lines =
marriage
89
Vertical line and brackets =
connect parent to offspring
90
A shaded circle or square =
person has the trait
91
A circle or square NOT shaded =
an individual who does NOT have the trait
92
Partial shade =
carrier/ heterozygous for the trait
93
multiple alleles
3 or more alleles of the same gene that code for a single trait
94
In humans, blood types are determined by how many alleles?
3 alleles - A, B, and O
95
How many alleles from blood types do humans actually inherit?
inherit 2 alleles
96
Dominant Blood Type Alleles
A and B (codominance)
97
Recessive Blood Type Alleles
O
98
What are possible blood types?
```
A = AA or AO
B = BB or BO
AB = AB
O = OO
```
99
mutation
sudden genetic change (change in base pair sequence of DNA)
100
How can mutations be?
- harmful
- beneficial
- neutral
101
Harmful mutations
organism less able to survive: genetic disorders, cancer, death
102
Beneficial mutations
allows organism to better survive: provides genetic variation
103
Neutral mutations
neither harmful nor helpful to organism
104
What are the two ways a mutation can occur?
chromosomal mutation or gene/point mutation
105
chromosomal mutation
- less common than a gene mutation
- more drastic – affects entire chromosome, so affects many genes rather than just one
- caused by failure of the homologous chromosomes to separate normally during meiosis
- chromosome pairs no longer look the same – too few or too many genes, different shape
106
What are examples of chromosomal mutations?
- Down syndrome
- Turner's syndrome
- Klinefelter’s syndrome
107
Down syndrome
(Trisomy 21) 47 chromosomes, extra chromosome at pair #21
108
Turner’s syndrome
- only 45 chromosomes, missing a sex chromosome (X)
| - Girls affected – short, slow growth, heart problems
109
Klinefelter’s syndrome
- 47 chromosomes, extra X chromosomes (XXY)
| - Boys affected – low testosterone levels, underdeveloped muscles, sparse facial hair
110
What can happen if there is an extra set of chromosomes in animals?
fatal in animals
111
What can happen if there is an extra set of chromosomes in plants?
it makes them larger and hardier
