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Bowman Biology 20A UCSC
EXam 2
146
Other
Not Applicable
02/17/2007

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Term
What is Mitosis?
Definition
Mitosis is the division of the nucleus
Term
Some cells can be _____-nuclear
Definition
multi
Term
______ _________ and mitosis usually are coordinated, but not always
Definition
Cell division
Term
What are chromosomes?
Definition
Chromosomes are the DNA, wrapped in special proteins.
Term
When Observing cells in a microscope there is a long ____ period.
Definition
Quiet
Term
When observing cells in a microscope the long quiet period is followed by what?
Definition
A short period when chromosomes are visible and divided between two cells
Term
When is DNA duplicated?
Definition
during the quiet period, interphase
Term
When do cells grow in size?
Definition
throughout the cycle
Term
In pulse labeling experiments what is added to cells?
Definition
Radioactive thymidine
Term
How long is the radioactive thymidine allowed to sit w/ cells in pulse labeling experiments?
Definition
30 min, then wash
Term
In pulse labeling experiments when would radioctive T be incorperated?
Definition
If cells are making DNA
Term
How are pulse labeled cells viewed?
Definition
Put on film, look for radioactivity
Term
Pulse labeling experiments:
_____ ______ not labeled in nucleus
Definition
Dividing cells
Term
Pulse labeling experiments:
Some _______ cells are labeled (most are not)
Definition
interphase
Term
Pulse labeling experiments analysis shows what?
Definition
How long each phase of the cell cycle lasts
Term
How does pulse labeling allow one to see how long each cell cycle phase lasts?
Definition
One can track radioactive T
Term
Pulse labeling experiments:
How long does M phase mitosis last?
Definition
0.3 - 1 h
Term
Pulse labeling experiments:
How long does G1 phase Gap 1 last?
Definition
~ 8 h
Term
Pulse labeling experiments:
How long does S phase Synthesis last?
Definition
~8 h
Term
Pulse labeling experiments:
How long does G2 phase Gap 2 last?
Definition
~5 h
Term
Many cells stop after __ phase, often called the __ ____ phase
Definition
M, G zero
Term
Mitosis, division of the nucleus starts as...?
Definition
chromosomes condense, become visible in light microscope.
Term
Because each chromosome is replicated it has two _________ ______.
These are ______, sometimes visible, often not visible.
Definition
identical halves, chromatids
Term
See constriction at one point, different arrangement of ___ and _____. Called the _______ (Special DNA sequences)
Definition
DNA, Protein, Centromere
Term
If it has a ___________ it is a chromosome.
Definition
Centromere
Term
Phases of Mitosis
Prophase
Definition
Chromosomes condense, Nuclear Envelope breaks down (probably into little vesicles)
Term
Metaphase
Definition
chromosomes line up in middle
at the metaphase plate.
Term
Anaphase
Definition
chromatids separate, thus the number of chromosomes doubles. Chromosomes move to opposite poles. Have two identical sets
Term
Telophase
Definition
Nuclear envelope reforms, get 2 nuclei
Term
Partitioning of chromosomes depends on a special apparatus made mostly of __________ and __________ _______.
Definition
microtubules, Microtubule motors
Term
"spindle" is an _________ of _________
Definition
Arrangement, Microtubules
Term
Role of the spindle:
________ is the organizing structure
Definition
Centrosome
Term
Composition and structure of centrosome?
Definition
Composition and structure is still unclear, made of special proteins
Term
In animal cells , the ______ are in the center of the
centrosome, made of __________
Definition
centrioles, Microtubules
Term
________ originate from centrosome, but don't obviously ______ to anything we can see.
Definition
Microtubules, connect
Term
___________ Move to each pole, _____ form, overlap from ______ to pole
and from pole to _________
Definition
Centrosomes, Microtubules, Pole, Chromosome
Term
MTs attach to the _________, a special protein structure located at the centromere
Definition
kinetochore
Term
each chromosome has a kinetochore for each ________. Thus one side of a _______ is attached to one pole and the other side to the other pole.
Definition
chromatid, chromosome
Term
MT thus move the chromosomes to the __________ _________.
Definition
Metaphase plate
Term
Anaphase movement caused by
1.?
2. ?
Definition
1.MTs push the poles apart.
2. The kinetochore pulls the chromosome along the MT
Term
What is Cytokinesis ?
Definition
Division of the whole cell.
Term
Cytokinesis involves?
Definition
Different mechanisms than mitosis
Term
In animals cytokinesis, appears to involve primarily ______ and _______
Definition
actin, Myosin
Term
Actin forms a ____ around the area to be divided, attached to the ______ ______
Definition
ring, Plasma membrane
Term
in cytokinesis Myosin causes the ring (of actin) to _______
Definition
contract
Term
The new cell is _________ _____ like a balloon
Definition
Pinched off
Term
In plant cells the thin wall cannot be __________ ________
Definition
squeezed together
Term
In plant cells the thin wall cannot be squeezed together ______ deliver ____ and ________ material to the region were
a new wall is to form
Definition
Vesicles, Wall, Membrane
Term
The cell cycle is highly _______, specific proteins _______ each step.
Definition
regulated, trigger
Term
Cell fusion experiments:
M phase + any other phase=?
Definition
Chromosomes condense
Term
splicing together M phase cells with other phase cells suggests what?
Definition
Suggests a factor can trigger beginning of chromosome condensation and perhaps mitosis.
Term
S phase cells + G1 phase =?
Definition
G1 cells start DNA replication
Term
S phase cells + G2 phase=?
Definition
G2 do not replicate DNA.
Term
What does S-phase cell splicing suggest?
Definition
Suggests factor that triggers S phase
Term
Cytoplasm from M-phase cells con be injected into large cells (oocytes) what does this trigger?
Definition
This triggers M-Phase (hypothetical MPF, M-phase promoting factor)
Term
What is the MPF?
Definition
Cyclin and a specific kinase are the MPF
Term
Why is cyclin called cyclin?
Definition
called cyclin because it cycles,
Term
How does cyclin cycle?
Definition
disappears when M is
complete, rises until activity get high enough to trigger mitosis.
Term
What does cyclin bind?
Definition
Binds an enzyme, a kinase
Term
What are kinases?
Definition
Kinases are enzymes that use ATP to phosphorylate other molecules, including other specific proteins.
Term
What does phosphorylation do?
Definition
Phosphorylation often acts as an ON or OFF switch for enzymes.
Term
When is the kinase in MFP active?
Definition
Active only when it is bound to cyclin
Term
When is MFP kinase present in the cell?
Definition
The kinase in MPF is always present
Term
What is the MFP kinase named?
Definition
named cyclin-dependent kinase (cdk)
Term
Rise in cyclin -->?
Definition
binds & activate cdk
Term
Rise in cyclin --> binds & activate cdk --> ?
Definition
phosphorylate and activate proteins needed for mitosis
Term
Rise in cyclin --> binds & activate cdk --> phosphorylate and activate proteins needed for mitosis --> ?
Definition
mitosis
Term
cell cycle Coordination achieved by using what?
Definition
Checkpoints
Term
Cells has mechanism (not understood) to determine if all _________ are aligned on the ______ ________ during mitosis.
Definition
chromosomes, metaphase plate
Term
G1 checkpoint
Definition
Determine if conditions are right for replicating DNA. (sufficient nutrients? Cell right size?)
Term
G2 checkpoint
Definition
Are chromosomes fully replicated? Cell right size?
Term
_______ have been identified that lack these checkpoints
Definition
mutants
Term
Cancer is caused by _____ __ _______ of the cell cycle.
Definition
loss of control
Term
Uncontrolled cell division can produce ?
Definition
benign and malignant tumors.
Term
Cells that keep dividing, but stay in one place=?
Definition
benign tumors, can get very large
Term
Serious problem occurs if cells _____________, move to other parts of the body.
Definition
metastasize
Term
Most cells stop in ___ or have limited _____ _____
Definition
G1, life span
Term
Example ______ _____ in blood, in the serum, can trigger division
Definition
growth factors
Term
Some cells will only grow in culture if ________ is present.
Definition
serum
Term
Tumor suppressors ?
Definition
proteins that have a normal function of keeping cell division turned 0ff
Term
How was retinoblastoma protein discovered?
Definition
by investigating an inherited cancer of children
Term
retinoblastoma protein?
Definition
Rb
Term
Rb binds the ___ protein
Definition
E2F
Term
unbound E2F stimulates _______
Definition
s-phase
Term
If Rb is defective, E2F is always ON, = ?
Definition
uncontrolled cell division
Term
Rb is an example of a ________ _________ _____
Definition
tumor suppressor gene.
Term
Cell cycle and Cancer illustrates the use of _________ ________ __________
Definition
Signal transduction pathways
Term
Growth factors -> ?
Definition
synthesis of cyclin
Term
Growth factors -> synthesis of cyclin --> ?
Definition
activate cdk
Term
Growth factors -> synthesis of cyclin --> activate cdk --> ?
Definition
phosphorylate Rb
Term
Growth factors -> synthesis of cyclin --> activate cdk --> phosphorylate Rb
--> ?
Definition
releases and activates E2F
Term
rowth factors -> synthesis of cyclin --> activate cdk --> phosphorylate Rb --> releases and activates E2F --> ?
Definition
activates DNA replication
Term
Cancer can be caused by..... (3 things)
Definition
Excessive growth factors
Turning on cyclin at wrong time
Defects in tumor suppressors
Term
Backup protections exist for most signals, thus ....?
Definition
multiple gene control defects must occur before a tumor will develop.
Term
Metastasis requires that cells survive ...?
Definition
outside of their normal environment.
Term
Metastasis requires that
Definition
Many protective systems have to fail.
Term
What is meiosis for?
Definition
Need to make haploid gametes.
Term
Are humans haploid or diploid?
Definition
Humans are diploid = two sets = 2N
Term
What kind of ploidy can plants have?
Definition
Some plants are polyploid -triploid, tetraploid, hexaploid
3,4, 6 set, 3N, 4N, 6N.
Term
Two chromosomes with the same set of genes are..?
Definition
"homologs" "homologous chromosomes"
Term
Meiosis - two major functions
Definition
Reduces chromosome number
Allows for recombination (new combinations) of genes.
Term
Two successive divisions
Definition
First one has special features

Second division like mitosis
Term
Meiosis I?
Definition
Chromosomes condense, form pairs,
recombination occurs.
Then chromatids do not split, instead, homologs separate and Migrate to poles.
Term
Meiosis II
Definition
Chromosomes move again to middle of cell
Sister chromatids separate move to the poles, form new nuclei
Term
Because there are two successive divisions (in meiosis) with no duplication of the
chromosomes
Definition
diploid nucleus --> haploid
Term
Two chromosome, each with two chromatids, form a ______
Definition
tetrad
Term
The process of formation (of a tetrad) is called ________.
Definition
synapsis
Term
Can see formation of _______, places where crossing over occurs
Definition
chiasma
Term
Meiosis produces enormous ________ in genetic inheritance
Definition
variation
Term
A description of an organism's set of chromosomes is called a..?
Definition
Karyotype.
Term
Humans have ___ different kinds(of chromosomes), including _ and _
Definition
23, x, y
Term
Missing or extra chromosomes cause major problems such as..?
Definition
Down syndrome, trisomy 21
Term
Down syndrome, trisomy 21 Caused by ?
Definition
both pairs of a chromosome moving to the same pole - called nondisjunction (failure to separate)
Term
Life cycles, diploid vs haploid stages:
Humans, most animals and plants, are almost always ________
Definition
diploid
Term
Meiosis occurs in specialized cells that give rise to ________
Definition
gametes
Term
Some plants, e.g. ferns, have both haploid and diploid forms .....?
Definition
"alternation of generations"
Term
Many microorganisms are ______
Definition
haploid
Term
Most fungi almost always ________, when gametes fuse, immdiately go into ________, produce _______ spores
Definition
haploid, meiosis, haploid
Term
Heredity - two previous ideas
Definition
Blending inheritance, e.g. blood lines, essences
Inheritance of acquired characteristics.
Term
Gregor Mendel
Genetic Experiments with..?
Definition
peas
Term
What pea charicteristics did mendel study?
Definition
Seed shape, seed color, pod shape and color, flower color, height, flower
Position on stem
Term
Experiment #1 cross yellow seed with green seed
result?
Definition
Result: 100% yellow (F1, first filial generation, sons and daughters)
Term
Experiment #1 cross yellow seed with green seed
Crossed F1 to F1
Definition
Got mix of yellow and green (F2 2nd filial generation) a 3:1 ratio
Term
Mendels interpretation of his results.?
Definition
1. Traits are carried as individual factors (we know them as genes)
2. For a given trait the factors can exist in alternative forms
Term
Gene
Definition
A discrete unit of genetic info... consisting of specific nucleotide sequence on DNA
Term
Allele
Definition
Alternative versions of a gene that produce distinguishable phenotypic effects
Term
dominant allele
Definition
an allele that is fully expressed in the phenotype of a heterozygote
Term
recessive allele
Definition
an allele whose phenotypic effect is not observed heterozygote
Term
genotype
Definition
the genetic makeup or set of alleles of an organism
Term
phenotype
Definition
the physical and physiological traits of an organism, which are determined by its genetic makeup
Term
Heterozygous
Definition
having two alleles for a given gene
Term
homozygous
Definition
having two identical alleles for a given gene
Term
a genetic locus
Definition
A specific place along the length of a chromosome where a given gene is located
Term
use of symbols e.g. Y and y
Definition
Y- dominant y- recessive
Term
Mendel's Principle of Segregation..?
Definition
two alleles for a given trait seperate during gamete formation and end up in different gametes
Term
genetics predicts __________
Definition
probability
Term
Two factor crosses
you get a _________ ratio
Definition
9:3:3:1
Term
Principle of Independent Assortment
Definition
each pair of alleles segregates independantly of other pairs of alleles during gamete formation
Term
Genes on the same chromosome only separate if.......?
Definition
parts of the chromosome are
exchanged during crossing over in meiosis.
Term
Measure percentage of recombination, 1% =
Definition
1 map unit.
Term
Genes far apart on chromosomes behave as though they are ....?
Definition
unlinked
Observe recombination 50% of the time.
Term
Linkage experiments allow us to map ....?
Definition
the location of genes
Construction of linkage maps
Term
sex chromosomes -
Some insects, Drosophila, See a pair of _____ ____________ in the females,
one of these appears in the eggs.
Definition
long chromosomes
Term
sex chromosomes -
Some insects, Drosophila, see a _____ and a ______ __________ in the males, distributed 50:50 in the
sperm.
Definition
long, short chromosome
Term
Sex chromosomes in drosophila called..?
Definition
Called X and Y, Same situation in humans
Term
The y chromosome has _____ _____ ______
Definition
few active genes.
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