Unit 5 Flashcards
1
Q
What is genetics?
A
The study of heredity + heredity variation
2
Q
What is heredity?
A
the transmission of traits from one generation to the next
3
Q
How are traits passed from parents to offspring?
A
genes
4
Q
What are genes?
A
segments of DNA that code for basic units of heredity
5
Q
How do offspring acquire genes from parents?
A
by inheriting chromosomes
6
Q
What does mean when offspring are clones?
A
offspring are exact copies of parent
7
Q
What is the only source of variation in asexual reproduction?
A
mutations
8
Q
How can one produce asexually?
A
through mitosis
8
Q
What are homologous chromosomes?
A
a pair of chromosomes that are the same size, same length, and same centromere position, that carry the same genetic information
9
Q
Where do each homologous chromosomes come from?
A
one from mom, one from dad
9
Q
What are karyotypes?
A
a display of chromosomes pairs ordered by size and length
10
Q
What are somatic cells?
A
Body cells, diploid (two complete sets of each chromosome)
11
Q
What are gametes cells?
A
Sex Cells, Haploid (one set of each chromosome)
12
Q
What has DNA that is packaged in chromosomes?
A
Eukaryotes
13
Q
What are the two types of chromosomes?
A
- autosomes
- sex chromosomes
14
Q
What are autosomes?
A
chromosomes that do not determine sex
15
Q
How many autosome pairs do humans have?
A
22
16
Q
What are sex chromosomes?
A
x and y
- eggs : x (humans: 22 + x)
- sperm : x or y (humans: 22+x, 22+y)
17
Q
What is a life cycle?
A
sequence of stages in the reproductive history of an organism from conception to its own reproduction
18
Q
What alternates in sexual life cycles?
A
fertilization and meiosis
19
Q
What is fertilization?
A
when a sperm cell (haploid) fuses with an egg (haploid) to form a zygote (diploid)
20
Q
Do all sexually reproducing organisms have both types of chromosomes?
A
yes
21
Q
What is meiosis?
A
a process that creates haploid gamete cells in sexually reproducing diploid organisms
22
Q
Compared to a parent cell, how many chromosomes will a daughter cell have after meiosis?
A
half
23
What does meiosis produce?
sperm and eggs that are haploid
24
What are the two rounds of division that are involved in meiosis?
- meiosis 1
- meiosis 2
25
Where does mitosis occur?
in somatic cells
26
How many divisions are involved in mitosis?
1
27
What is the result of mitosis?
2 diploid daughter cells
28
What is significant about the daughter cells that came from mitosis?
they are genetically identical
29
What does meiosis form?
gametes (sperm + eggs)
30
How many divisions are involved in meiosis?
2
31
What is the result of meiosis?
4 haploid daughter cells
32
What is significant about the daughter cells that come from meiosis?
they are genetically unique
33
What are the 3 key events of meiosis?
1) Prophase 1
2) Metaphase 1
3) Anaphase 1
34
What happens in prophase 1 of meiosis?
synapsis + crossing over
35
What happens in metaphase 1 of meiosis?
tetrads (homologous pairs) line up at the metaphase plate
36
What happens in anaphase 1 of meiosis?
homologous pair separate
37
What happens in interphase of meiosis 1?
cells go through G1, S (DNA is copied), and G2
38
What does synapsis mean in prophase 1?
Homologous chromosomes pair up and physically connect to each other forming a tetrad
39
Where does crossing over occur in prophase 1?
at the chiasmata
40
What happens during crossing over in prophase 1?
DNA is exchanged between the homologous pairs
41
What does each chromatid that is produced from crossing over have?
a unique combination of DNA
42
What happens in Metaphase 1?
independent orientation: tetrads line up at the metaphase plate
43
What happens in anaphase 1?
pairs of homologous chromosomes separate
- sister chromatids are still attached
44
What happens in telophase 1 and cytokinesis?
- nuclei + cytoplasm divide
- after that there is a haploid set of chromosomes in each daughter cell
45
What happens in prophase 2?
- no crossing over
- spindle forms
46
What happens in metaphase 2?
- chromosomes line up at the metaphase plate
- because of crossing over in meiosis 1, the chromatids are unique
47
What happens in Anaphase 2?
sister chromatids separate and move towards opposite poles
48
What happens in telophase 2 and cytokinesis?
- 4 haploid cells
- nuclei reappears
- each daughter cell is genetically unique
49
What is the equation for a parent cell in early meiosis 1?
2n=4
50
What is the equation for each daughter cell at the end of telophase 2 and cytokinesis?
n = 2
51
How does crossing over lead to genetic variation?
produces recombinant chromosomes : they exchange genetic materials
52
How does independent assortment of chromosomes lead to genetic variation?
chromosomes are randomly oriented along the metaphase plate during metaphase
53
How does random fertilization lead to genetic variation?
any sperm can fertilize any egg
54
What ensures genetic diversity in sexual reproducing organisms?
meiosis followed by fertilization
55
What provides genetic information that plays a role in natural selection?
meiosis followed by fertilization
56
What is meiosis driven by?
subcellular components
57
What is free energy used for in meiosis?
growth and reproduction of living systems
58
What carries genetic information?
DNA + RNA
59
What shares the genetic code?
all living systems
60
What is true breeding?
organisms that produce offspring of the same variety over many generations of self pollination
61
What is the P generation?
true breeding parental generation
62
What is the F1 generation?
(first filial) hybrid offspring of P generation
63
What is the F2 generation?
(second filial) offspring of the F1 generation
64
What is a punnett square?
diagrams used to predict the allele combinations of offspring from a cross with known genetics compositions
65
What do capital letter mean in punnett square?
dominant traits
66
What do lower case letter mean in punnett square?
recessive traits
67
What does homozygous mean?
an organism that has a pair of identical alleles for a character
68
What does heterozygous mean?
an organism that has two different alleles for a gene
69
What is genotype?
the genetic makeup (allele) of an organism
70
What is phenotype?
an organisms appearance, which is determined by the genotype
71
What do testcrosses help determine?
if the dominant trait is homozygous dominant or heterozygous
72
What are the two fundamental principals of heredity founded by mendel?
1) the law of segregation
2) the law of independent assortment
73
What are alleles?
alternative versions of a gene
74
What are monohybrid crosses?
a cross between the F1 Hybrids
75
What is the law of independent assortment?
genes for one trait are not inherited with genes of another trait
76
What does the law of independent assortment apply to?
1) genes that are located on different chromosomes (not homologous)
2) genes that are very far apart on the same chromosome
77
What is dihybrid cross?
a cross between F1 dihybrids
78
What is meant by the term "true breeding"?
a true breeding plant or animal is one that will always pass down a specific phenotype trait
79
Differentiate between the P, F1, and F2 generation
P: parental generation
F1: first filial, offspring of the parental generation
F2: second filial, offspring of the F1 generation
80
What is the difference between an organism's genotype and an organism's phenotype?
- an organisms genotype is its genetic makeup
- an organisms phenotype is the appearance, which is determined by phenotype
81
What is stated by the laws of segregation and independent assortment?
- law of segregation states that the two allele for the same trait separate during gamete formation and end up in different gamete
- law of independent assortment states that genes for one trait are not inherited with genes of another trait
82
What do the laws of segregation and independent assortment reflect?
rules of probability
83
What is the multiplication rule?
the probability that two or more independent event will occur together in some specific combination?
84
What is the addition rule?
the probability that two or more mutually exclusive events will occur
85
What pedigrees?
family trees that give a visual of inheritance patterns of particular traits
86
What does a square represent in pedigrees?
male
87
What does a circle represent in pedigrees?
female
88
What does a horizontal line connect in pedigrees?
parents
89
What does a vertical line connect in pedigrees?
children
90
Do dominant traits ever skip a generation?
no
91
What does it mean if a trait is X-linked, in regards to males and females?
males are more commonly affected than females
92
Why do many traits not follow the ratios predicted by Mendel's laws?
- varying degrees of dominance
- may have multiple genes acting together
- traits may be determined by genes on sex chromosomes
- genes may be adjacent or close to one another on the same chromosome and will segregate as a unit
- some traits may be the result of non nuclear inheritance
93
True or false: alleles can show varying degrees of dominance
true
94
What type of dominance did the traits in Mendel's experiments have?
complete dominance
95
true or false: homozygous dominant and heterozygous individuals are phenotypically the same
true
96
What is incomplete dominance?
when neither allele is fully dominant
97
What makes up the phenotype of the F1 generation?
a mix of those of the parental generation
98
What is codominance?
when two alleles that affect phenotype are both expressed
99
What are multiple alleles?
genes that exist in forms with more than two alleles
100
In most cases, how many genes are responsible in determining phenotypes?
two or more
101
What is epistasis?
the phenotypic expression of a gene at one locus affects a gene at another locus
102
What is polygenic inheritance?
the effect of two or more genes acting on a single phenotype
103
What is a sex linked gene?
a gene located on either the X or Y chromosome
104
What are Y linked genes?
genes specifically found on the Y chromosome
105
What are X linked genes?
genes found on the X chromosome
106
To whom can fathers pass x linked alleles down to?
all of their daughters, but none of their sons
107
To whom can mothers pass down x linked alleles down to?
both daughters and sons
108
In females, what happens if an x linked trait is due to a recessive allele?
females will only express the trait if they are homozygous
109
In males, what happens if an x linked trait is due to a recessive allele?
because males only have one x chromosome, they will express the trait if they inherit it from their mother
- they are called hemizygous
- due to this males are much more likely to have an x linked disorder
110
What is Duchenne muscular dystrophy?
progressive weakening of muscles
111
What type of disorder is Duchenne muscular dystrophy?
x linked disorder
112
What is hemophilia?
inability to properly clot blood
113
What type of disorder is hemophilia?
inability to properly clot blood
114
What is color blindness?
inability to correctly see colors
115
What type of disorder is color blindness?
x linked disorder
116
How many x chromosomes do females inherit compared to males?
two x chromosomes, which is double than males
117
What happens to most x chromosomes in each cell during development?
becomes inactive
118
During development, what does the inactive x chromosome in each cell of a female do?
condenses into a Barr body
119
What does the x chromosome condensing to a barr body help regulate?
gene dosage in females
120
What is genetic recombination?
production of offspring with a new combination of genes from parents
121
What is parental types?
offspring with the parental phenotype
122
What is recombinants?
offspring with phenotypes that are different from the parents
123
What are linked genes?
genes located near each other on the same chromosomes that tend to be inherited together
124
What is meiosis and random fertilization generate genetic variation in offspring due to?
- independent assortment of chromosome
- crossing over in meiosis I
- any sperm can fertilize any egg
125
When do linked genes show parental phenotypes?
in offspring at higher than 50%
126
What happens during crossing over?
chromosomes from one paternal chromatid and one maternal chromatid exchange corresponding segments
126
When will you have a higher probability that a crossing over event will occur between genes?
the further apart two genes are on the same chromosome
126
What does it mean for the recombination frequency if two genes on the same chromosome are further apart?
it will be higher
126
What is a linkage map?
a genetic map that is based on recombination frequencies
127
What are map units?
the distance between genes
128
What is one map unit equivalent to?
a 1% recombination frequency
129
T or F : some traits are located on DNA found in the mitochondria and chloroplasts
True
130
How are both chloroplasts and mitochondria assorted to gametes and daughter cells?
randomly
131
In animals, how are mitochondria transmitted?
by the egg NOT the sperm
132
In plants, how are mitochondria and chloroplasts transmitted?
in the ovule NOT the pollen
133
How are all mitochondrial DNA in animals inherited?
maternally
134
How are both mitochondrial and chloroplast determined traits inherited in plants?
maternally
135
What is a Chi square?
a form of statistical analysis used to compare the actual result (observed) with the expected results
136
What do Chi squares help determine?
- whether the data obtained experimentally provides a "good fit" to the expected data
- if any deviations from the expected results are due to random chance alone or to other circumstances
137
What is the chi square designed to analyze?
categorical data
138
What are observed (actual) values?
the numbers you get in your data (usually no calculations)
139
What are expected values?
based on probability (need to do calculations)
140
What is step one of a chi square?
determine what your expected and observed values are
141
What is step two of a chi square?
make a table
142
What is step three of a chi square?
plug in your data to the table and solve
143
What is step four of a chi square?
determine the degrees of freedom of your experiment
144
What must you do with X squared?
you must determine the probability that the difference between the observed and expected values occurred simply by chance
145
What is the equation for degrees of freedom?
number of categories - 1
146
How do you interpret the results if 2 squared is greater than the critical value?
there is a statistically significant difference between the actual and expected values
147
How do you interpret the results if 2 squared is less than the critical value?
there is NOT a statistically significant difference between the actual and expected values (accept null hypothesis)
148
What row should you look at on the degree of freedom chi square table unless instructed otherwise?
p=0.05
149
T or F : various environmental factors can influence gene expression and lead to phenotypic plasticity
True
150
What do individuals with the same genotype exhibit in different environments?
different phenotypes but does not change gene
151
What can be linked to affected or mutated alleles or chromosomal changes?
genetic disorders
152
What is tay sachs disease?
- autosomal recessive disease
- mutated HEXA gene (the body fails to produce an enzyme that breaks down a particular fluid)
- affects central nervous system and results in blindness
153
What is sickle cell anemia?
- autosomal recessive disease
-mutated HBB gene (sickled cells contain abnormal hemoglobin molecules)
154
What is nondisjunction?
when chromosomes fail to separate properly in meiosis I or meiosis II
155
What can detect nondisjunction?
karyotyping
156
How are traits passed from parents to offspring?
through genes
157
Where does mitosis occur?
in somatic cells
158
What are the big ideas of mitosis?
1 division, results in 2 diploid daughter cells, and daughter cells are genetically identical to parent cells
159
What are the big ideas of both mitosis and meiosis?
both are processes of cell division, they use the same steps for cell division, synthesis of DNA occurs in both
160
What are the big ideas of meiosis?
forms gametes, 2 divisions, results in 4 haploid daughter cells, each daughter cell is genetically unique
161
What kind of cells does meiosis form?
haploid sex cells (during fertilization, a sperm cell will fertilize an egg to create a 2n zygote)
162
What is the haploid number of the sex cells that meiosis forms?
n=12
163
How many cells does meiosis start and end with?
starts with 1 and ends with 4
164
How many chromosomes do the diploid cells from meiosis have?
4
165
What are the key events in meiosis?
prophase I, metaphase I, and anaphase I
166
Where do crossing over events occur?
between homologous chromosomes
167
What does the exchange of genetic information (crossing over) create?
recombinant chromosomes that are unique from the parent cell's DNA
168
What leads to genetic variation?
- crossing over events
- independent assortment of chromosomes
- random fertilization
169
What does the independent assortment of chromosomes mean?
chromosomes can orient with either the paternal or maternal chromosomes closer to a certain pole
170
What does random fertilization mean?
any sperm can fertilize any egg
171
T or F : in sexual reproduction there isn't genetic variation
False, in sexual reproduction there is a vast amount of genetic variation
172
What are offspring that are produced in asexual reproduction?
clones (identical to their parent, unless mutation occurred)
173
What could have happened if Mendel did not study pea plants?
He may not have created the law of segregation and the law of independent assortment
174
Describe how a test cross can be used to determine whether a dominant trait is homozygous or heterozygous?
by reviewing the offspring and their phenotypes, if any of the offspring show the recessive phenotype, then it can be assumed that the parent with the dominant allele is heterozygous
175
Differentiate between the law of segregation and the law of independent assortment?
Law of segregation states that two alleles for the same trait separate during gamete formation and end up in different gametes
Law of independent assortment says the alleles of two (or more) different genes get sorted into gametes independently of one another
176
What type of cross would give a 3:1 ratio?
A monohybrid cross
177
What type of cross would give a 9:3:3:1 ratio?
A dihybrid cross
178
If a red flower is crossed with a white flower, and the resulting offspring are pink, what is the easiest way to explain these results?
Incomplete dominance
179
If a red flower is crossed with a white flower, and the resulting offspring are both red and white, what is the easiest way to explain these results?
Codominance
180
Why are there very few Y-linked disorders?
The Y chromosome is very small and contains little genetic information compared to the X chromosome
181
True or False, If an x-linked trait is due to a recessive allele, females will only express the trait if they are heterozygous.
False, homozygous
182
If a trait is inherited that is on mitochondrial DNA, did the trait come from mom or dad?
Mom, mitochondrial DNA is inherited through the egg in animals and the ovule in plants
183
Describe the possible ways that gametes can be formed with an incorrect number of chromosomes?
- Nondisjunction-occurrence
- Deletion
- Inversion
- Translocation
184
Whose the smartest person in this class?
Emmy
