Exam 4 Flashcards
(212 cards)
1
Q
What is mitosis?
A
A single “parent” cell divides resulting in 2 “daughter” cells
2
Q
A
3
Q
What does mitosis accomplish with unicellular organisms?
A
Asexual reproduction
4
Q
What does mitosis accomplish with multicellular organisms?
A
Growth and repair
5
Q
Definition of meiosis?
A
A single “parent” cell divides resulting 4 “daughter” cells
6
Q
What are daughter cells?
A
Gametes (eggs or sperm)
7
Q
Are gametes genetically identical or unique?
A
Unique
8
Q
Does meiosis accomplish asexual or sexual reproduction?
A
Sexual reproduction
9
Q
What is DNA?
A
The inherited information-containing molecule
10
Q
Where is DNA located?
A
In the nucleus of cells
11
Q
What are genes?
A
Discrete segments of DNA that code for specific proteins
12
Q
How does DNA exist?
A
As very long molecular strands called chromosomes
13
Q
How many genes are in a chromosome?
A
Thousands
14
Q
How many chromosomes do human cells have?
A
46
15
Q
Name for diffuse state that chromosomes exist in?
A
Chromatin
16
Q
What happens to chromosomes when the cell is not dividing?
A
They are in chromatin; spread throughout the nucleus and individually cannot be distinguished
17
Q
When are chromosomes duplicated?
A
When the cell is preparing to divide
18
Q
Where are chromatids attached at?
A
Centromere
19
Q
What do chromosomes wrap and coil around?
A
Histone proteins
20
Q
A
21
Q
A
22
Q
What is the cell cycle?
A
Sequence of stages between when a cell is first produced by cell division and when it in turn divides
23
Q
What percent of the cell cycle is spent in interphase?
A
90%
24
Q
What is happening during interphase?
A
The cell is not dividing but growing
25
How many phases does interphase have?
3; G1, S, G2
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What happens during G1 phase?
The cell performs its normal functions, with cell growth
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What is produced during G1 phase?
New cytoplasm (organelles and cytosol)
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What state are chromosomes in during G1?
Diffuse chromatic
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What happens during the S phase?
Chromosomes duplicate, DNA synthesis
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What happens during the G2 phase?
Cells perform normal functions, cells continue to grow, chromosomes still exist as chromatin
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What happens to DNA in G2 phase?
Each chromosome now has 2 chromatids, so DNA has doubled
32
What percent of the cell cycle is spent in the mototic phase?
10%
33
During what phase does cell division occur?
Mitotic phase
34
The mitotic phase consists of _____ and ______
Mitosis, cytokinesis
35
What is mitosis?
The division of the nucleus
36
What is cytokinesis?
The division of the cytoplasm
37
What are the 4 stages of mitosis?
Prophase, metaphase, anaphase, telophase
38
Cytokinesis occurs simultaneously with ____
Telophase
39
Acronym for the 4 continuous stages of mitosis?
PMAT- please move across the cell
40
What coils around histones and become individually distinct?
Chromosomes
41
What moves toward opposite "poles" of the cell in prophase?
Centrosomes
42
What manufactures the mitotic spindle?
Centrioles
43
What are centrioles made out of?
Microtubules
44
The ____ extends from each centrosome
Mitotic spindle
45
What breaks down during prophase?
Nuclear Envelope
46
What are kinetochores?
Specific centromere proteins where spindle microtubules attach to
47
During metaphase, the _____ ______ aligns with the _____ at the ______ of the cell
Mitotic spindle; chromosomes; "equator"
48
What is the metaphase plate?
"equator" of the cell
49
What happens to the spindle microtubules attached to the chromosome's centromeres during anaphase?
They shorten
50
What happens during anaphase?
Chromatids pulled apart, are now individual chromosomes
51
What happens to spindle microtubules that extend across the cell during anaphase?
They lengthen
52
What happens when the spindle microtubules lengthen?
They push the poles further apart, elongating the cell
53
What happens during telophase?
Chromosomes have now reached opposite poles of the cell, and the mitotic spindle breaks down
54
What happens when the chromosomes are on opposite poles of the cell?
A nuclear envelope forms around each pole and chromosomes return to the chromatin state
55
A _______ _____ forms in animal cells during cytokinesis
Cleavage furrow
56
What begins shallow but deepens in ctokinesis?
Ring of microfilaments
57
The ____ ____ is cleaved down its center, pinching the parent cell into ____ _____ ______ daughter cells
Elongated cell; 2 genetically identical
58
What forms during cytokinesis plant cells?
A cell plate
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____ with cell wall material are _____ in the _____ of the elongated cell
Vesicles; deposited; center
60
Vesicles fuse to form a?
Cell plate
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What does the cell plate fuse with?
Cell wall of the parent cell
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Are the daughter cells of plant cells cytokinesis genetically identical or unique
Identical
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What is the term for a chromosome pair?
Homologous chromosome
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A gene for a particular trait is found at the _____ ______ on both homologous chromosomes
Same location
65
What is the name for the specific physical location for a gene?
Locus
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Examples of somatic cells?
Human skin, nails, body cells
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An organisms body cells are called?
Somatic cells
68
How many pairs of homologous chromosomes do human somatic cells contain?
23
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How many pairs of homologous chromosomes are called autosomes?
22 pairs
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Genes for traits other than _____ are located on _____
Gender; autosomes
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How many pairs are called sex chromosomes?
1 pair
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What do sex chromosomes determine?
Gender
73
An XX individual is?
Female
74
An XY individual is?
Male
75
What does meiosis do?
Separate chromosomes of a homologous pair producing cells with half the number of chromosomes
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What are cells called in meiosis?
Gametes
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The human life cycle is the sequence of stages between ____
The adults of one generation and the adults of the next generation
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What are human somatic cells called?
Diploid
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What do diploid cells have?
Both members of each homologous pair of chromosomes
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2n=?
46
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What are gametes called?
Haploid
82
What do haploid cells have?
One member of each homologous pair of chromosomes
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n=?
23
84
Haploid gametes (eggs and sperm) are produced by?
Meiosis
85
Where are haploid gametes produced?
In the gonads (ovaries and testes)
86
What is the fusion of gametes?
Fertilization
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What produced a single cell called a zygote?
Fertilization
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Are zygotes diploid or haploid?
Diploid
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What happens with fertilization?
A zygote receives one member of each homologous pair from the egg (from mom) and the other member of each homologous pair form the sperm (from dad)
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Meiosis is the?
Reducing the chromosome number from diploid to haploid
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Fertilization is the?
Reestablishing of diploid chromosome number
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What do meiosis and fertilization form the basis of?
Sexual reproduction
93
Cell division during which a _____ cell gives rise to ______ ______ ____
Diploid; four haploid gametes
94
In what state are the chromosomes during interphase?
Chromatin
95
What do chromosomes do during chromatin in interphase?
They duplicate to form sister chromatids
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Where are chromosomes attached at?
Centromeres
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Stages of Meiosis?
Interphase, Meiosis I, Meiosis II
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What happens during meiosis I?
A diploid cell divides, producing 2 haploid cells
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What happens during Meiosis II?
2 haploid cells divide, producing 3 haploid cells (gametes)
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First stage of meiosis I?
Prophase
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The joining of 2 homologous chromosomes is termed?
Synapsis
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2 homologous chromosomes X 2 sister chromatids each=?
Tetrad
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What occurs during prophase I? (meiosis)
Crossing over
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What pairs up in prophase I? (meiosis)
Homologous chromosomes
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What coils tightly around histones and become individually distinct?
Chromosomes in prophase I
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What happens to the centrosomes in prophase I? (meiosis)
The 2 of them move toward opposite poles of the cell
107
Centrioles manufacture a spindle of?
Microtubules
108
The spindle extends from ?
Each centrosome
109
What breaks down in prophase I? (meiosis)
Nuclear envelope
110
Where do the spindle microtubules attach to the chromosomes at centromeres? (meiosis)
Kinetochores
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What happens do spindle microtubules in meiosis I? (meiosis)
Each spindle microtubule attached to only one member of each homologous pair
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What happens during Metaphase I? (meiosis)
The homologous pairs of chromosomes (tetrad) are aligned at the equator of the cell
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The spindle microtubules attached to chromosomes' centromeres in anaphase I _____? (meiosis)
Shortern
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The spindle microtubules that extend across the entire cell in anaphase I _____? (meiosis)
Lengthen
115
What remains attached during anaphase I? (meiosis)
Sister chromatids
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What happens to homologous chromosomes during telophase I? (meiosis)
They reach the opposite poles of the cell
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What forms during telophase I? (meiosis)
Nuclear envelopes
118
Do chromosomes return to the chromatin state during telophase (Meiosis)
No
119
What breaks down in telophase (meiosis)?
The Spindle
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Difference between cytokinesis in animals and plants?
Animals- cleavage furrow, plants- cell plate
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Are the daughter cells haploids or diploids in meiosis I?
Haploid, with half the number of chromosomes as the parent cell
122
What does Meiosis II consist of?
Prophase II, metaphase II, anaphase II, telophase II
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During meiosis II each cell begins and ends with a _____ chromosome number
Haploid
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During mitosis each cell begins and ends with a _____ chromosome number
Diploid
125
Genetic variation is essential for?
Evolution identical offspring
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Asexual reproduction produce?
Genetically identical offspring
127
Sexual reproduction produces?
Genetically unique offspring
128
What consists of crossing over, independent assortment of chromosomes and random fertilization?
Meiosis and fertilization
129
Is the orientation of homologous pairs of chromosomes during metaphase I random?
Yes
130
How many possible chromosome combinations are there for a human gamete?
About 8 million
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What is random fertilization?
A random egg is fertilized by a random sperm
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For the resulting zygote how many possible chromosome combinations are there?
64 trillion
133
What does crossing over produce?
Recombinant chromosomes with genetic information distinct from the parental chromosomes
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During what phase are small segments of non-sister chromatids on homologous chromosomes exchanged?
Prophase I
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What is the name for sites of crossing over?
Chiasmata
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What do errors during meiosis do?
They alter the number of chromosomes within cells
137
What is nondisjunctoin?
A failure of chromosomes to separate during meiosis
138
What fails to separate during anaphase I?
Homologous chromosomes
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What fails to separate during anapahse II?
Sister chromatids
140
What results in gametes with an abnormal number of chromosomes?
Nondisjunction
141
Zygotes resulting from fertilization of abnormal gametes with have what?
Abnormal chromosome numbers
142
2n+1=?
Trisomy
143
2n-1=?
Monosomy
144
Do abnormalities pass to all somatic cells as the zygote grows by mitosis?
Yes
145
What does nondisjunction result in very early during pregnancies?
Spontaneous abortion (miscarriages)
146
What is trisomy 21?
condition involving an extra 21st chromosome
147
Condition number for down syndrome?
2n+1 condition
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XYY
Normal male
149
XXX
Normal female
150
XXY
Klinefelter syndrome
151
XO
Turner syndrome
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What is genetics the study of?
Heredity
153
What is heredity?
The transmission and inheritance of traits from one generation to the next
154
P generation?
Parent generation
155
F1 generation?
First generation of offspring- produced by mating of P individuals
156
F2 generation
2nd generation of offspring, produced by mating of F1 individuals
157
What are genes?
Discrete segments of DNA
158
What are hereditary units that carry information coding for particulat traits?
Genes
159
What are alleles?
Alternative forms of a gene
160
Example of a gene?
Eye color
161
Example of alleles?
Brown, blue, green- alleles for eye color
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How many genes does an organisms inherit from each parent?
One
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What does it mean to be homozygous?
2 alleles are the same
164
What does it mean to be heterozygous?
2 alleles are different
165
If an organism is heterozygous, how many alleles are expressed?
One
166
What does it mean to be dominant?
The expressed allele in a heterozygous organism
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What does it mean to be recessive?
The allele is not expressed in a heterozygous organism
168
Masked defintion?
Has no noticeable effect
169
What is the genetic makeup of an organisms combination of alleles?
Genotype
170
What is phenotype?
The expressed physical traits of an organism, outward expression of the organism's genotype
171
Homozygous dominant (AA) genotype
Dominant phenotype
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Homozygous recessive (aa) genotype
Recessive phenotype
173
Heterozygous (Aa) genotype
Dominant phenotype
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Who was the first to establish the principles of genetics?
Gregor mendel
175
When was Gregor Mendel experimenting with pea plants?
1860's
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Pea plants possess ____ possible alleles for each of the _____ visible traits
Two; seven
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Pea plants have male and female reproductive structures on the same flowers so they can do what?
Self-fertilize
178
What did Mendel was to control and ensure?
Cross fertilization
179
What did Mendel to ensure cross-fertilization?
Removed male structures from certain plants, then pollinated female structures of these plants with pollen taken from other plants
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What is a cross between individuals differing in just one trait?
Monohybrid cross
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What did Mendel mate?
Homozygous dominant parent plants (PP; purple flowers) with homozygous recessive parent plants (pp; white flowers)
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What color did the offspring F1 exhibit?
All of them showed dominant purple flowers
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What color showed when Mendel mated plants of F1 generation with each other?
3/4 dominant purple, 1/4 recessive white
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An individual has _____ alleles for each trait because chromosomes occur in _____ pairs
Two; homologous
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Alleles for the same gene are found at the ____ on both homologous chromosomes called the _____
Same location; locus
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What is Mendel's law of segregation?
During Meiosis homologous chromosomes separate, gametes carry only 1 allele for each trait
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what brings homologous chromosomes together?
Fertilization of gametes
188
What is the punnett square used for?
Predict and display the results of genetic crosses
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A monohybrid cross between 2 individuals heterozygous results in?
3:1 phenotypic ratio (3 dom: 1 rec), 1:2:1 genotypic ratio (1 homo: 2 hetero: 1 homo)
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What offspring can result betwen a homozygous dom male (WW) and a homozygous rec female (ww)?
All offspring are heterozygous (Ww)
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What are the possible offspring between 2 heterozygotes? (Ww)
3 Ww: 1 ww
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What is the probability that 2 heterozygous parents (Ww x Ww) have 4 children with (ww)?
1/4x1/4x1/4x1/4= 1/256= .39%
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What is dihybrid cross?
Cross between individuals differing in 2 traits
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Mendel mated homozygous dom parents plants (RRYY) with homozygous rec parent plants (rryy), what did the offspring exhibit?
All offspring showed dominant
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What is Mendel's law of independent assortment?
Each pair of alleles segregates independent of all other pairs during gamete formation, the inheritance of 1 character has no effect on inheritance of any other characters
196
What does a dihybrid cross between 2 individuals heterozygous for 3 traits result in?
9:3:3:1 phenotypic ration- 9 dom for both, 3 dom for 1st trait, 3 rec for 1st trait but dom for 2nd, 1 rec for both traits
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A _____ cross is equivalent to two separate ____ crosses
Dihybrid ; monohybrid
198
What is the chromosome theory of inheritance?
Chromosomes sort and separate randomly during meiosis- carrying their alleles with them
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The behavior of chromosomes during meiosis explains Mendel's two laws called?
Law of segregation, law of independent assortment
200
What are testcrosses used to determine?
Unknown genotypes
201
If an individual displays a recessive phenotype, the genotype must be?
aa
202
If an individual displays a dominant phenotype, the genotype could be?
AA, Aa
203
How was the testcross used by Mendel?
To ensure the pea plants in his parent generation were homozygous dominant and not heterozygous
204
Pedigree analysis is used to determine?
Unknown genotypes
205
What does pedigree analysis analyze?
The matings that have already occured
206
How do recessive disorders happen?
Due to homozygous recessive combination of alleles
207
Examples of recessive disorders?
Genetic deafness, cystic fibrosis
208
Why do recessive disorders persist?
Because heterozygous individuals who do not have the disorder are carriers of the allele for the disorder
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Is it likely that 2 individuals carrying a rare recessive allele will meet and mate?
No
210
Dominant disorders are due to what?
A homozygous dominant or heterozygous combination of alleles
211
Examples of dominant disorders?
Genetic Alzheimer's disease, huntington's disease
212
Why do dominant disorders persist?
Because they occur later in life
