bio exam 4 Flashcards
(154 cards)
1
Q
binary fission definition
A
the cell division process that prokaryotic cells replicate by
2
Q
4 step process of binary fission
A
- DNA replication
- chromosome segregation
- cytokinesis
- cell separation
3
Q
what happens in step 1, DNA replication, of binary fission
A
the chromosome is duplicated so that the cell has 2 complete copies of its DNA sequences
4
Q
what happens in step 2, chromosome segregation, of binary fission
A
the 2 copies of the chromosome are physically separated to the opposite ends of the cell
5
Q
what happens in step 3, cytokinesis, of binary fission
A
the cell membrane pinches in the middle to separate the 2 cells
6
Q
what happens in step 4, cell separation, of binary fission
A
the pinched membrane combines with itself so that the 2 separate cells are made
7
Q
interphase definition
A
the periods between rounds of mitosis
8
Q
3 major steps of interphase
A
- first gap (G1)
- synthesis (S)
- second gap (G2)
9
Q
what happens in S phase of interphase
A
the cells chromosomes are copied
10
Q
what happens in G1 of interphase
A
growth and performance of physiological jobs; most of the cells life
11
Q
what happens in G2 of interphase
A
preparation for mitosis
12
Q
similarities between prokaryotic and eukaryotic chromosomes
A
- supercoiling
13
Q
differences between prokaryotic and eukaryotic chromosomes
A
prokaryotic:
- 1 chromosome circular in shape
- kept in the cytoplasm (nucleoid)
eukaryotic:
- many chromosomes linear in shape
- kept in nucleus
- wrapped around histones
- nucleosome
14
Q
- basic structure
- number
- shape
of human chromosomes during interphase
A
- loosely packed ball of chromatin
- chromatin fill out entire nucleus
- x shaped structures
- 46 total
15
Q
- basic structure
- number
- shape
of human chromosomes during mitosis
A
- copied chromosomes from S phase
16
Q
homologous chromosome definition
A
the chromosomes of each pair from parent
17
Q
sister chromatid definition
A
the identical copies of each homologous chromosome
18
Q
centromere definition
A
region of the chromosomes where the sister chromatids are attached together
19
Q
cohesin proteins definition
A
proteins used to stick the two sister chromatids together at the centromere
20
Q
kinetochore definition
A
the protein based structure that the mitotic spindle attaches to the chromosomes at
21
Q
stages of mitosis and what happens in each
A
- prophase - chromatin condense into dense, distinct mitotic chromosomes
- prometaphase - nuclear envelope breaks apart and releases chromosomes into cytoplasm; mitotic spindle attaches
- metaphase - mitotic spindle lines up with homologous chromosomes in middle of cell
- anaphase - enzymes destroy cohesions holding the sister chromatids together; pulled to opposite ends of cell
- telophase - nuclear envelope reforms around segregated chromosomes; chromosomes into chromatin
- cytokinesis - mitotic spindle breaks down and cells separate
22
Q
difference of cytokinesis in animal cells vs plant cells
A
animals:
1. spindle breaks down
2. ring of protein attaches to plasma membrane and pinches membrane together
3. membrane combines with itself to produce 2 separate cells
plants:
1. spindle remains
2. spindle assembles vesicles made by golgi in middle of the cell (vesicles contain materials to build cell walls)
3. vesicles combine forming cell plate (creates 2 separate cells)
4. spindle breaks down
23
Q
2 types of reproduction
A
- sexual
- asexual
24
Q
how do the parent genetics compare to the offspring in sexual reproduction
A
genetically different from parent
25
how do the parent genetics compare to the offspring in asexual reproduction
genetically identical to parent
26
somatic cells definition
perform all of the body's normal functions outside of reproduction
27
germ cells defiition
produce specialized cells for reproduction called gametes
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how many sets of chromosomes do somatic cells typically have
2 complete sets
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how many sets of chromosomes do germ cells typically have
1 complete set
30
haploid definition
cells that have 1 complete set of chromosomes
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diploid definition
cells that have 2 complete sets of chromosomes
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2 mating type in gametes
1. anisogamy
2. isogamy
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anisogamy definition
gametes differ in size and shape
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isogamy definition
gametes are same in size and shape
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how does sexual reproduction complete with fertilization
one cell of each type will fuse together
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zygote definition
a single diploid cell produced by fertilization
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how many sets of chromosomes does a zygote typically have
2 sets
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what kind of cell begins meiosis
diploid germ cell
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what kind of cells are produced in meiosis I (and are they haploid or diploid)
2 haploid
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what kind of cells are produced in meiosis II (and are they haploid or diploid)
4 haploid
41
what happens in meiosis I prophase
the nuclear envelope breaks down and the chromosomes physically connect together in a structure called a bivalent chromosome, then crossing-over happens
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what happens in meiosis I metaphase
the chromosomes attach to the spindle then line up at the middle of the cell
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what happens in meiosis I anaphase
bivalents break down and homologous chromosomes are separated to the ends of the cell by the mitotic spindle
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what happens in meiosis I telophase
spindle breaks down but the nucleus does not re-form
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what happens in meiosis II prophase
the spindle reforms
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what happens in meiosis II metaphase
chromosomes line up at the middle of the cell
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what happens in meiosis II anaphase
sister chromatids are separated
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what happens in meiosis II telophase
spindle breaks down and nucleus reforms around sister chromatids
49
how does prophase I of meiosis differ from prohpase in mitosis
mitosis:
- homologous chromosomes remain separate from each other
meiosis:
- they physically connect together
50
bivalent chromosome definition
have 2 homologous chromosomes physically connected together
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synapsis definition
the physical connection of chromosomes
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synaptonemal complex definition
formed when the chromosomes become glued together by a set of proteins
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crossing-over definition
during synapsis, when the homologous chromosomes are able to swap entire sections of their DNA with each other
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chiasma definition
each spot on the chromosomes where crossing-over happens
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how does metaphase I of meiosis differ from metaphase in mitosis
mitosis:
- homologous chromosomes remain separate from each other so each individual chromosome will line up at the middle of the cell
meiosis:
- they line up randomly as bivalents
56
independent assortment definition
the unique and randomly generated set of parental chromosomes that each cell produces by mitosis
57
why does meiosis produce cells that are genetically unique from their parents
the parental chromosomes end up on each side of the cell randomly
58
3 parts of a nucleotide and what they are used for
1. sugar with 5 carbon atoms -
2. phosphate group -
3. nitrogen containing base -
59
describe the complete structure of a DNA molecule
- polymer of nucleotides
- sugar deoxyribose
- sugars and phosphates hold chain together with covalent bonds (backbone)
- asymmetrical
- backbones face outside
- bases face middle
- held by hydrogen bonds between bases
- duble helix antiparallel
- groves alternate along strand
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strand definition
a single DNA strand
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directionality definition
the property of DNA that when DNa polymers are made, new nucleotides can only be added where there is a free 3-prime -OH group
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backbone definition
the chain of sugars and phosphates
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complementarity definition
the principle when because of the base pairing rules, the order of nucleotides of one DNA strand can always be determined from the base pair sequence on the opposite DNA strand
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double helix definition
both strands must be twisted into a spiral shape
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antiparallel definition
when the two strands of DNA must be oriented in opposite directions
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major groove definition
the larger gap - where the geometry of the DNA double helix is such that there are between the two backbones there are gaps that are different sizes
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minor groove definition
the smaller gap - where the geometry of the DNA double helix is such that there are between the two backbones there are gaps that are different sizes
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how are nucleotides used for energy storage
they carry chemical energy in their easily hydrolyzed phosphoanhydride bonds
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what are the nucleotides used in DNA
purines: adenine, guanine
pyrimidines: thymine, cytosine
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rules of base pairing
A - T
G - C
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major function of DNA
to store information (specifically, to make one or more proteins or RNA molecules)
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gene definition
the sequences of DNA that contain information to make protein or RNA
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genetic / DNA sequence definition
the order of bases in a DNA strand, read in a straight line from the 5-prime end to the 3-prime end
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gene expression definition
the process of using the generic information to make RNA and protein
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coding DNA definition
approximately 20% of chromosomal DNA are genes
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non-coding DNA definition
80% of chromosomal DNA has a variety of functions
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what is the principle of complementarity
the principle when because of the base pairing rules, the order of nucleotides of one DNA strand can always be determined from the base pair sequence on the opposite DNA strand
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why is the foundation of DNA replication the property of complementarity
each strand in DNA replication is used to make a copy of the other using the POC
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describe the process of replication initiation:
- what is it
- where does it start
- what happens during
- occurs simultaneously at multiple places on a chromosome
- sites where it starts are called replication origins
- forms replication bubble. strands at the bubble are separated
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replication bubble definition
the structure formed in the very first stage of DNA replication
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replication fork definition
the area where DNA replication happens
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bidirectional definition
(DNA replication from the origin) each traveling in different directions
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how is DNA synthesized by DNA polymerase
DNA polymerase catalyzes a chemical reaction that removes and releases 2 phosphates from the nucleotide and forms a covalent bond between the 3-prime OH on the new strand and the phosphate on the nucleotide
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proofreading definition
other major function of DNA polymerase
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why does the DNA polymerase need to proofread
improperly paired bases will distort the molecular shape of the DNA strand
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how does the DNA polymerase proofread
the polymerase senses the distortion, which activates a second enzyme activity in DNA polymerase called an exonuclease, which removes the wrong base by hydrolyzing the covalent bond, then polymerase goes back and adds the correct nucleotide using its synthesise enzyme
87
genome definition
describes all of the genetic instructions contained within a cell or virus
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gene definition
many individual instructions which make up chromosomes and other genetic material
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gene expression definition
the process by which the information encoded in a gene becomes a trait of a cell or organism
90
what is the importance of proteins to cells
they are responsible for forming most of the structures and carrying out most of the functions of life
91
why must cells turn the instructions in their genes into proteins
to stay alive and perform the necessary functions of life
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3 rules of central dogma
1. genetic information needed to make all of the proteins of the cell is stored in the sequence of the DNA molecules of the cells genome
2. information stored in a genes DNA sequence is copied into an RNA sequence using the process of transcription
3. information transcribed into an RNA sequence is used by the ribosomes of the cell to make a protein using the process of translation
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transcription definition
the process where using the information stored in DNA first requires it to be copied into an RNA molecule
94
translation definition
the process using the information transcribed into an RNA sequence used by ribosomes to make a protein
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what happens during transcription
1. DNA base pairs are temporary separated by breaking the hydrogen bonds
2. genetic sequence in DNA is read from beginning to end
3. as it is being read, a copy of that sequence is made using the rules of complementarity
96
coding strand definition
the strand that will be copied
97
template strand definition
the strand that is read by the RNA polymerase
98
RNA polymerase definition
the enzyme that performs transcription
99
DNA vs RNA structure differences
DNA:
- bases ATGC
- deoxyribose sugar
- double stranded
RNA:
- bases AUGC
- ribose sugar
- single stranded
100
how are base pairing rules different in RNA
G - C
T - A
A - U
101
where do transcription and translation happen is eukaryotic cells
nucleus, then the mRNA is transported to cytoplasm
102
where do transcription and translation happen is prokaryotic cells
cytoplasm
103
basic structure of a protein
long chain of amino acids (typically hundreds) which are chemically bonded by peptide bonds
104
protein sequence definition
the order of amino acids in proteins if they were to be read
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codon definition
3 letter words that the genetic sequence of an RNA molecule is organized into
106
how are codons translated into an amino acid sequence with the genetic code
each codon corresponds to a particular amino acid in the protein sequence
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significance of MET codon
start codon; tells the ribosome when to start translating the mRNA
108
significance of STOP codon
tells ribosome when the protein is complete and to stop translating
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how does translation occur
the ribosome slides along an mRNA molecule and reads the codons of the genetic sequence and creates the new protein chain
110
how is tRNA used in the translation process
(transfer RNA) will form base pairs with the mRNA which allows it to carry the correct amino acid into the ribosome
111
mutation definition
heritable changes to a genetic sequence
112
how can a mutation result in changes to protein sequences and function
a protein’s amino acid sequence will determine how it folds and any changes to that sequence can change its folding
113
3 types of mutation
1. insertion
2. deletion
3. substitution
114
(mutation) insertion definition
when one or more nucleotides in the genetic sequence are permanently added, becoming longer than normal
115
(mutation) deletion definition
when one or more nucleotides in the genetic sequence are permanently removed, becoming shorter than normal
116
(mutation) substitution definition
when one nucleotide base is replaced with another, staying the same length
117
4 types of mutation effects
1. silent
2. missense
3. nonsense
4. frameshift
118
how do frameshift mutations work
when insertions and deletions happen, it shifts the genetic sequence because the codons are changed
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why can frameshift mutations cause extreme changes in proteins
premature stops, completely altered proteins
120
2 ways that mutation can happen and their cause
1. spontaneous - because of errors in the processes that copy DNA molecules or repair damage to them
2. induced - caused by the presence or intense radiation or chemicals that can damage DNA structure
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mutation rate definition
the frequency in which cells make errors resulting in spontaneous mutations in the cell
122
how do mutation rates compare in:
- eukaryotic cells
- bacterial cells
- viruses
eukaryotes < bacteria < viruses
123
why do microbial cells mutate much more rapidly than humans even though they have a similar mutation rate
bacteria can mutate every time they go through cell division, every 30min-2hrs
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heredity definition
the transmission of physical traits from parents to offspring
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trait definition
any observable characteristic of an individual
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polymorphic trait definition
traits that come in multiple forms
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phenotype definition
the specific version of a trait that an individual has
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gene definition
a region of the DNA of a chromosome that contains the information needed to produce a protein or RNA molecule
129
where do the specific traits and phenotypes from an individual come from
the collective action of that individual's genes
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why are most traits polymorphic
most genes of a species exist in multiple forms (called alleles)
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what are the 2 alleles of cystic fibrosis and what happens at the cellular level for each
1. normal - normal functional protein in cell membrane
2. CF - gets trapped in the endoplasmic reticulum
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genotype definition
the specific combination of alleles that any one individual has
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possible genotypes of CF
1. FF - both normal
2. Ff - one normal one misfold
3. ff - both misfolded
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dominant allele definition
only one copy needs to be present for its phenotype to be expressed
135
recessive allele definition
both copies need to be present for its phenotype to be expressed
136
which CF alleles are dominant or recessive
F (normal) - dominant
f (CF) - recessive
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homozygous definition
both dominant or both recessive
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heterozygous definition
one dominant, one recessive
139
what do Mendelian genetics allow us to do
1. predict the genotypes and phenotypes of the offspring of two parents
2. use the genotypes and phenotypes of the offspring to predict the genotypes of the parents
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which aspects of meiosis do the rules of Mendelian genetics come from
comes from the way chromosomes are separated in meiosis
141
how to determine genotypic ratio and phenotypic ratio by building punnet square
genotypic ratio:
- homozygous dominant
- homozygous recessive
- heterozygous
phenotypic ratio:
- dominant trait
- recessive trait
142
4 assumptions / limitations of Mendelian genetics and why they are sometimes not true
1. genes only have 2 alleles
2. each trait is determined by the action of a single gene
3. genes are unchanging
4. genes and traits are expressed uniformly throughout the lifespan of an organism
143
co-dominance definition
have multiple dominant alleles that do not blend their traits
144
explain how co-dominance works using ABO blood type example
6 genotypes:
IAIA, IAi, IBIB, IBi, ii, IAIB
4 phenotypes:
IAIA and IA = type A
IBIB and IB = type B
IAIB = type AB
ii = type O
145
incomplete dominance definition
when dominant and recessive traits blend together
146
explain how incomplete dominance works using sickle cell trait example
2 alleles:
HA, HS
3 genotypes and phenotypes:
HAHA = functioning
HSHS = sickle cell anemia
HAHS = sickle cell trait
147
epistasis definition
when the effect of one gene can be altered or hidden by another
148
explain how epistasis works using ABO blood type example
some people with a type A or type B genotype have type O blood
149
pleiotropy definition
when a single gene can change the development of multiple traits
150
explain how pleiotropy works using sickle cell disease example
sickle cell (single trait) causes many changes in body systems (skin damage, eye damage, blood clots, high blood pressure, heart disease)
151
polygenic trait definition
complex traits that arise from the action of multiple genes
152
how are polygenic traits typically expressed
normal distribution (bell curve)
153
how do traits develop along a normal distribution (average is most common, above and below become more rare)
the average trait is the most common in individuals and in the middle of the curve, and the further you travel from that middle the less people that have it
154
how can environmental factors influence development of traits (using examples of human height and siamese cats)
height:
- availability of food
- level of physical activity
- exposure to pollution
- economic status
siamese cats:
- have an allele in genes that determines coat color, and the enzyme tyrosinase is sensitive to temperature
- activity makes them darker
- inactivity makes them white
