Chapter 8 Flashcards
double stranded helical nucleic acid,
DNA
unit of hereditary information consisting of a specific nucleotide sequence
gene
carrying structure containing DNA and proteins
Chromosome
the noncondensed form of DNA and proteins present when the cell is not dividing
Chromatin
Is binary fission an example of sexual or asexual reproduction?
Asexual
How many chromosomes do bacterial cells have?
1
A single-celled eukaryote, like an amoeba, would reproduce by ___________.
binary fission
Are the two cells resulting from binary fission genetically identical or unique?
identical
Organisms that are the result of sexual reproduction have a pair of chromosomes, one from each parent. A human somatic (body) cell has 46 chromosomes. How many chromosomes are inherited from each parent?
23
In humans, a sperm cell would have _____ chromosomes
23
The body cell of a dog has 78 chromosomes. How many chromosomes are in a dog egg cell?
39
T/F The number of chromosomes correlates to the complexity of the organism. For example, a complex organism like a human will always have more chromosomes than a ‘lower’ organism like a tree.
FALSE
How many chromosomes are found in a human zygote?
46
In humans, a cell from the liver would have _____ chromosomes.
46
Most organelles duplicate during the ___ phase in order to prepare for becoming two separate cells, both of which will need a set of organelles.
G1 phase
How many chromosomes are present during the G1 phase in humans?
46
Which two organelles duplicate themselves independently and separately from the rest of the cell cycle?
mitochondria and chloroplast
How many chromatids are present during the S phase in humans?
92
Based on the illustration of the cell cycle, the cell spends most of its time in which phase?
interphase
If the chromosomes were to not line up in metaphase, would each new daughter cell have the correct number of chromosomes?
no
What would happen if the spindles did not attach to each chromosome?
the chromatids may fail to separate
Choose the purposes of mitosis:
Growth
Gamete formation
cell replacement
asexual reproduction
Growth, asexual reproduction, cell replacement
Which of the following types of animal cells would you expect to have a fast (frequent) rate of mitosis?
skin
A fish embryo would have a _____ rate of cell division.
fast
Which of the following disappear during telophase?
Nuclear envelope
Mitotic spindle
Nucleolus
mitotic spindle
The imaginary line where the chromosomes line up in the center of the cell is called the _______________.
Mitosis plate
metaphase plate
middle plate
mitochondria plate
Metaphase plante
Which of the following reform during telophase?
nuclear envelope
mitotic spindle
Centrosomes
Nuclear envelope
Which of the following has disapeared by the end of prometaphase?
mitotic spindle
sister chromatids
centromere
nuclear envelope
centrosome
Nuclear envelope
Cytokinesis overlaps with which two phases of the cell cycle?
Anaphase and telophase
Are daughter cells resulting from mitosis genetically unique or identical?
Identical
In humans, how many chromosomes are in each daughter cell following mitosis?
46
Which phase of the cell cycle is the longest?
interphase
How would mutations on a gene controlling the G2 checkpoint contribute to the formation of a cancer?
It would allow cells with inaccurate DNA replication to divide.
If there is abnormal growth of cells that never leaves the original tissue and has well-definied edges, it is classified as a ____________________ tumor.
benign
You look into a microscope and see cells that growing together so each cell is touching another cell or surface. You then notice that the cells are continuing to grow on top of eachother. You would conclude that this may be a mutation in the genes that signal for (control of):
contact inhibition
If the cells of a tumor break off and travel to a different part of the body and begin a tumor in the new location the cancer is said to
have metastisized
A cell has a diploid (2n) number of 4. How many chromosomes will be present in each of the resulting haploid (n) cells?
2
If a wombat has 40 chromosomes, how many chromosomes must be in each egg/sperm to ensure that the offspring will have the correct number of chromosomes?
20
In humans, which sex chromosomes would genetically denote a female?
XX
Homologous chromosomes are _______ to each other.
Similar
T/F? Even though they carry different genes, sex chromosomes behave as a __________________.
homologous pair
In which phase is DNA duplicated?
S Phase of Interphase
Sister chromatids align at the center of the cell.
Metaphase II
Tetrads separate, resulting in haploid cells
Anaphase I
Sister chromatids separate
Anaphase II
Tetrads align along the equator of the cell
Metaphase I
Occurs in body cells, such as skin, liver, and bone
Mitosis
Crossing over
Prophase I
4 separate cells form that are genetically unique
Telophase II/Cytokinesis
DNA duplicates
Interphase
Occurs in the ovaries and testes of animals
Meiosis
During which phase of meiosis are the sister chromatids separated?
Anaphase II
During which phase of meiosis are the homologous chromosome pairs separated?
Anaphase I
In humans, how many chromosomes does each daughter cell have after MEIOSIS II?
23
In humans, how many chromosomes does each daughter cell have after MEIOSIS I?
23
In humans, how many chromosomes does each daughter cell have after MITOSIS?
46
Which of the following contribute to genetic variation?
crossing over
independent orientation
mutation
mitosis
binary fission
random fertilization
Crossing over, independent orientation, random fertilization, mutation
Match:
XXX
Trisomy 21
XO
XXY
————-
Down’s syndrome
“Metafemale”
Turner’s syndrome
Klinefelter’s syndrome
XXX: Metafemale
Trisomy 21: Downs
XO: Turners
XXY: Klinefelters
Which of the following disorders involve autosomes?
Down’s syndrome
Which of the following would be easiest to view under a microscope?
chromosomes
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?
In the centrosomes.
Organisms produced as a result of binary fission exhibit ______ genetic variation.
no
During which phase(s) of mitosis do we find chromosomes composed of two chromatids (duplicated chromosome)?
from G2 of interphase through metaphase
All of the following occur during mitosis except:
the formation of a spindle.
the condensing of chromosomes.
the disappearance of the nucleolus.
the uncoupling of chromatids at the centromere.
the synthesis of DNA.
Synthesis of dna
Which of the following does not occur during mitosis?
packaging of the chromosomes
replication of the DNA
spindle formation
separation of the centrosomes
separation of sister chromatids
Replication of DNA
The genetic material is duplicated during
S phase
The haploid (n) number of chromosomes is found in nearly ______ cells of humans and most other animals.
sex cells
The genetic material is duplicated during
the mitotic phase.
mitosis.
G2
G1
the S phase.
The S Phase
Organisms produced as a result of binary fission exhibit ______ genetic variation
no
A microtubule organizing center (__________) is located at _________ of the dividing cell in both plants and animals.
centrosome
each pole
Viruses and chemical exposure can cause mutations in ___________ which can lead to cancer.
proto-oncogenes
In some organisms, mitosis occurs without cytokinesis occurring. This will result in what?
A cell having more than one nucleus.
Which of the following organisms does not use mitosis to make another cell?
mushroom
banana tree
bacterium
cow
cockroach
Bacteria
How do the daughter cells at the end of mitosis compare with their parent cell when it was in G1 of the cell cycle?
The daughter cells have the same number of chromosomes and the same amount of DNA.
One difference between a cancer cell and a normal cell is that:
Cancer cells continue to divide even beyond their boundaries.
During which phase(s) of mitosis do we find chromosomes composed of two chromatids (duplicated chromosome)?
from G2 of interphase through metaphase
T/F? Binary fission uses a spindle (network of microtubules made by centrosomes) for the separation of daughter chromosomes, just as in mitosis.
FALSE
DNA replication occurs in the ____ stage of interphase just before _______.
last; mitosis
Contact inhibition stops normal cells from dividing when they ___________, but this is not functional in cancer cells.
come in contact with neighboring cells
DNA replication occurs in the _____ stage of ________ just before mitosis.
last stage of interphase
A ____________ ___________ ___________(centrosome) is located at each pole of the dividing cell in both _______ and _______
microtubule organizing center
both plants and animals.
How many individuals are required in asexual reproduction?
1 individual
Cell division in eukaryotes involves separate processes called __________ and __________
mitosis and cytokinesis
The centromere is a region in which:
chromatids of a duplicated chromosome are attached to one another and where the DNA is pinched in a bit.
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?
Centrosomere
T/F The haploid (n) number of chromosomes is found in nearly all body cells of humans and most other animals
FALSE
Chromosomes are aligned along the cell’s equator during ___.
The metaphase
T/F Binary fission uses a spindle (network of microtubules made by centrosomes) for the separation of daughter chromosomes, just as in mitosis.
FALSE
Brain cells (neurons) are constantly in _____ phase of interphase. This means that they _______ able to regenerate after injury.
G0
are not able to regenerate
A particular cell has not replicated its DNA yet. The cell in question is most likely in
G1
_______________ stops normal cells from dividing when they come in contact with neighboring cells, but this is not functional in ______ cells
Contact inhibition, cancer cells
In anaphase II of meiosis the ________ are split, breaking the _________.
chromatids
Centromere
T/FSources of genetic variation in a sexually reproduction arises only from fertilization.
FALSE
Another name for a tetrad is a ______.
bivalent
Spindle fibers connect to the ______ fibers meiosis.
Kinetochore
Crossing over occurs during ____________
Prophase I.
t/f Meiosis leads to gametogenesis, oogenesis, and spermatogenesis.
TRUE
T/F? The centromere holds the homologous chromosomes together in meiosis II.
FALSE, the centromere is broken
T/F DNA is replicated between meiosis I and meiosis II.
FALSE, S phase of Interphase
The chromosome ______ are located at the metaphase plate during metaphase I.
tetrads
A failure of meiosis can lead to ____ number of genes in a gamete and therefore inviable gametes.
Increased
T/F the centromere holds the ______________ together in meiosis II.
sister chromatids
T/F The events of meiosis II are most similar to interphase.
FALSE
Each gamete contains _____ sex chromosome(s)
1
In meiosis, chromosomes are aligned in the center of the cell by ___________
spindle fibers.
Alignment of the chromosomes during metaphase I leads to _____________________
variation of genetic material.
T/F? At the end of meiosis II, the chromosomes consist of sister chromatids held together at a centromere.
FALSE
The microtubule spindle apparatus originates from the _________
centrosomes
There is/are ______ division(s) in meiosis.
2
_______ are arranged along the equator during metaphase I
Tetrads
T/F? Meiosis leads to gametogenesis, oogenesis, and spermatogenesis.
TRUE
The replication of DNA and the duplication of genes occurs during _______
S phase of Interphase
In meiosis the daughter cells are genetically ___.
Different
T/F? The microtubule spindle apparatus originates from the plasma membrane.
FALSE
In anaphase II of meiosis the ___________ are split, breaking the ____________
chromatids, centromere
During anaphase I the association between members of a tetrad is _______and they ________.
disrupted, seperate
The cell formed through fertilization is called a _______.
zygote
T/F Homologous chromosomes are similar in size, similar in shape and location of the centromere, and carry the genetic code for the same traits.
TRUE
Homologue separation occurs during ________of meiosis.
anaphase I
The ___________ holds the sister chromatids together in meiosis I.
centromere
If DNA replication has already occurred, the chromosomes consist of ____________ held together at a centromere.
sister chromatids
If there is any damage to the DNA the cell will try to repair the damage before allowing the cell to continue to the _______ of the cell cycle
S phase
If a sperm contains 4 chromosomes, it comes from an animal that has __ chromosomes
8
If DNA replication has already occurred, the chromosomes consist of sister chromatids held together at a __________.
centromere
Does asexual reproduction create genetically identical or adverse offspring?
Identical
Does sexual reproduction create genetically identical or adverse offspring?
Diverse
When is asexual reproduction beneficial?
You don’t need a mate, it takes less time and energy.
How is asexual reproduction bad?
More competition for resources and stable environment and no genetic diversity.
What are three benefits of sexual reproduction?
Having genetic diversity, having genes to adapt, evolution occurs easier.
What are some organisms that do asexual reproduction?
Bacteria, yeast, liver cells, starfish.
What are chromosomes?
Condensed DNA when cell is dividing.
What is chromatin?
Loose DNA when cell is not dividing.
What is a gene?
A unit of heredity found on a certain place on a chromosome that codes for a certain product.
What is DNA?
Your genetic blueprint.
What are chromosomes, chromatin, and genes made of?
DNA and proteins.
Where may they be found in the cell?
Nucleolus.
How many chromosomes are found in a human body cell? How many strands of chromosomes?
46 chromosomes, 92 strands.
How many genes can be found in a human cell?
Thousands
What isthe information in genes used for?
Making proteins and enzymes, growth and development of a cell, protecting the organism from infection, and ensuring fidelity of offspring to the parent.
Where do diploid cells come from?
2 haploid cells
What are somatic cells?
Body cells
Are somatic cells haploid or diploid?
Diploid
What is the notation for diploid?
2n
What are gametes?
Sex cells
Are gametes haploid or diploid?
Haploid
What is the notation for haploid?
1n
What does n stand for?
Number of chromosomes
What process do bacteria divide by?
Binary fission
How does binary fission work?
DNA replicates and a cell membrane forms between the 2 chromosomes, dividing them and forming 2 daughter cells.
In binary fission, are the 2 daughter cells genetically identical or diverse?
Identical
How many chromosomes do bacteria cells have?
1
Does the number of chromosomes correlate to the complexity of the organism?
No
Why are somatic cells diploid cells?
Because they have one set of chromosomes donated by each parent, resulting in TWO sets of chromosomes.
How is a zygote formed?
When two gametes combine through fertilization
What is the name for gametes found in males?
Sperm
What is the name for gametes found in females?
Egg/Ovaries
In humans, how many chromosomes are inherited from the mother? The father?
23 each
In humans, how many chromosomes are found in a gamete?
23 chromosomes.
After fertilization, will the resulting zygote be haploid or diploid?
Diploid
How many chromosomes are found in a human zygote?
46
The diploid number for a horse is 64. What is the haploid number?
32
How many chromosomes are in a horse gamete?
32
How many chromosomes are in a horse zygote?
64
What is the cell cycle?
A sequence of growth + division of a cell.
What does the cell cycle begin and end with?
1 parent cell, 2 daughter cells.
Is this an example of asexual or sexual reproduction?
Asexual
What are the three main stages of the eukaryotic cell cycle?
Interphase, Mitosis, Cytokinesis
Define interphase.
G1, G2, and S phase. Where DNA is replicated before mitosis. The cell contents are duplicated here.
Define Mitosis
separating of sister chromatids. Genetically identical daughter cells. Division of nucleus through PMAT.
Define Cytokinesis.
When the cytoplasm is dividing. Not part of mitosis.
What are the 4 sub-phases for interphase?
G0, G1, G2, and S phase.
Summarize G0 phase.
Normal cell functions, not dividing.
Summarize G1 phase.
Growth. Duplicating organelles + making proteins for mitosis.
Summarize S phase.
Synthesis phase. DNA replication. One set for each daughter cell.
Summarize G2 phase.
Growth. Replicating centrosomes.
What are centrosomes made up of?
2 centrioles.
When a cell is dividing, how many centrosomes and centrioles are present?
2 centrosomes and 4 centrioles.
Which 2 organells duplucate autonomously and separately from the rest of the cell cycle?
Mitochondria and Chloroplast
Why does the cell begin to make large amounts of proteins?
To fuel mitosis.
How many strands of DNA are present during the G1 phase in humans?
1 strand.
Are these cells n or 2n?
2n
How many strands of DNA are present during the S phase in humans?
1 strand, duplicated.
How many strands of DNA are present during the G2 phase in humans?
2 strands
What is a centromere?
Holds together 2 sister chromatids
What are sister chromatids?
Identical copies of each other produced during DNA replication
What is the purpose of checkpoints in the cell cycle?
To make sure the cell is okay to go onto the next phase.
What is the G1 checkpoint?
It cheks to make sure the cell has room to grow, and it checks for DNA damage.
The G1 checkpoint happens prior to what phase?
The S phase
Why must nutrients be available before more cells can be made?
Because the nutrients are needed for mitosis.
What is the G2 checkpoint?
It assesses DNA errors.
The G2 checkpoint happens prior to wha phase?
Mitotic phase.
How would a replication error in DNA affect the function of the new daughter cell?
The cell could be mutated and continue to produce the mutation, or the cell will program itself to die.
What is another word for the cell programing itself to die?
Apoptosis
What is the M checkpoint?
It checks for the spindle fivers attatched to the kinetochore.
The M checkpoint is prior to which phase?
Anaphase
If the cell fails these checkpoints after it has committed to divide, what will typically happen to the cell?
It will destroy itself.
Why would the cell go through such drastic measures to make sure mitosis occurs without error?
To make sure the daughter cells have the correct number of chromosomes.
What would happen if the cell did not divide properly and continued to pass the checkpoints, even when it should not pass?
The cells produced will have either 1 extra or 1 less chromosome, and they will be mutated.
What are growth factors?
Proteins that signal and communicate between the cells. They are needed to stimulate cell division.
What is Density Dependent?
Contact between cells inhibits further mitosis.
What is another name for density dependent?
Contact inhibition
Why would cells stop mitosing when they fill up a space?
Because the density is at full capacity, and there is no room to divide.
What term describes “cells must have an underlying surface on which to adhere in order to grow?”
Anchorage Dependent
What is mitosis?
Phase of the cell cycle where the nucleus divides.
What type of cellular reproduction is this?
Asexual
What are examples of cells that do NOT go through mitosis?
Sex cells, haploid cells, RBC, nerve cells, heart cells.
What are the 3 main functions of mitosis?
1) Growth + Development
2) Replacement of Cells
3) Asexual reproduction
What types of animal body cells have a fast rate of mitosis?
Skin cells
Does mitosis occur in somatic cells or gametes?
Somatic cells
What is the first stage of mitosis?
Prophase
What happens to DNA during prophase?
Chromatin form condenses into chromosomes.
What change has occured to the nuclear envelope? To the centrosomes?
The nuclear envelope and nucleolus start to disappear. The centrosomes start tp move to either pole of the cell.
What protein fivers attatch to the kinetochore proteins at the centromere of the chromosomes?
Spindle fibers
How many chromosomes are there in prophase? Sister chromatids?
46 chromosomes, 92 chromatids.
What is the second phase of mitosis?
Metaphase
What happens during metaphase?
The sister chromatids line up on the center of the cell.
What is the imaginary line called where the chromosomes line up in the center of the cell?
Metaphase plate.
What is guiding the chromosomes to the center?
Microtubules (spindle fibers)
Which phase is a checkpoint?
Metaphase.
What would happen if the chromosomes were not lined up in metaphase? Would each new daughter cell have the correct number of chromosomes?
Cell may give time to correct, or mitosis continues with wrong numbers of chromosomes in each sell.
No.
How many chromosomes are there in metaphase? Sister Chromatids?
46 Chromosomes, 92 Chromatids
What is the third phase of mitosis?
Anaphase
What happens during anaphase?
The chromatids are separated and pulled to either pole of the cell.
What happens to the duplicated chromosomes? The sister chromatids?
The centromeres come apart and the chromatids are separated. They are now called chromosomes.
What protein ‘fibers’ pull the chromosomes?
spindle fibers.
How many chromosomes are there in anaphase? Sister chromatids?
92 chromosomes, 0 chromatids.
How many chromosomes are on either pole in anaphase?
46 on either pole
What is the last stage of mitosis called?
Telophase
What happens during telophase?
The cell starts to pinch off. The form of the nucleus starts to come back.
What is a notable characteristic of telophase?
Clevage furrow.
What is a clevage furrow?
Where daughter cells are pinching off.
What happens to chromosomes in telophase?
They uncondense back into chromatin.
What change occurs to the nuclear envelope in telophase?
The appearance of it reforms.
How many chromosomes are there in telophase?
92 (46 on either end)
What is Cytokenisis?
The division of the cytoplasm into two daughter cells.
Which 2 phases of mitosis does cytokenisis overlap with?
Anaphase and telophase.
How many chromosomes are there in cytokenisis?
46 (in each daughter cell)
Which phase of the cell cycle is the longest?
Interphase.
Are the new cells from mitosis haploid or diploid?
Diploid
Are the daughter cells genetically identical or diverse
Identical because everything was copied and distributed evenly.
What are cancer cells the result of?
Multiple DNA mutations
How would mutations on cell checkpoint genes contribute to cancer?
Because cancer replicates without limit, so it ignores checkpoints.
What is a tumor?
An abromal mass.
What is a benign tumor?
One that doesn’t spread.
What is a malignant tumor?
One that spreads uncontrollably.
What is metastasis?
Spread of cancer cells.
What does it mean when a tumor has metastasized?
It has started to spread.
How do more aggressive cancers differ in terms of rate of mitosis?
They can break off and duplicate quickly in other places.
Does chemotherapy target cells with a slow or fast rate of mitosis?
Fast rate.
What is radiation and chemotherapy?
Radiation destroys cancer cells, and chemo is a drug that treats metastatic tumors. They disrupt the cell cycle.
What is meiosis?
Reduction division producing 4 haploid cells. Produces gametes
How many cell divisions occur in meiosis?
2
How many cell divisions occur in mitosis?
1
How many daughter cells are produced in mitosis?
2
Are daughter cells in mitosis haploid or diploid?
Diploid.
Cells in mitosis are _______
identical
How many gametes are produced from one parent cell in meiosis?
4
Are cells in meiosis haploid or diploid?
Haploid
Are cells in meiosis unique or identical?
Unique
Which cells do mitosis and meiosis occur?
Mitosis in somatic cells, meiosis in egg/testes.
How many pairs of chromosomes do diploid cells have?
23 pairs.
What are autosomal chromosomes?
Pairs of chromosomes that are common to men and women.
Which pair of chromosomes is different?
Sex chromosomes.
Which sex chromosomes do women have? Men?
XX, XY
What are homologous chromosomes?
Chromosomes in a matched pair. They can be copies or duplications. Each pair of chromosomes represents homologous chromosomes.
Are homologous chromosomes identical to each other?
No, but they are similar.
Are sex chromosomes always identical? Are they considered homologous?
They are not always identical, and they are considered homologous.
Why do gametes must only have one set of chromosomes?
Because when they fertilize, the zygote has a set from each parent to make all 46.
Hedgehogs have a diploid number of 90. How many chromosomes does a hedgehog zygote have?
90
In which phase is DNA duplicated?
In S phase of Interphase
Is there an interphase before meiosis I?
Yes
What happens in prophase I?
Replicated chromosomes condense, homologous pairs match up, crossing over occurs between homologous pairs, spindle forms, nuclear envelope disappears.
What are tetrads?
4 chromatids
What is the term used to describe what happens when homologous chromosomes pair up to form tetrads?
Synapsis
What is crossing over?
When homologous chromosomes exchange DNA segments, reuslting in non-identical chromatids.
What is the purpose of crossing over?
To create varation.
Why might crossing over be advantageous to the offspring?
Because it creates genetic variation
In prophase 1, how many duplicated chromosomes are present?
46 duplicated chromosomes
How many sister chromatids are present in prophase 1?
92
What happens in metaphase 1?
Paired homologous chromosomes (tetrads) align at the center of the cell.
How is the arrangement of chromosomes in metaphase 1 different from that of metaphase?
In metaphase 1, the tetrads are lined up, in metaphase, the sister chromatids are lined up.
In metaphase 1, how many duplicated chromosomes are present? Sister chromatids?
46, 92
What happens in anaphase 1?
Tetrads are split up and homologous pairs are pulled to either side of the cell.
Do centromeres separate in anaphase 1?
No, the centromeres and chromatids do not separate yet.
In anaphase 1, how many duplicated chromosomes are present? How many sister chromatids?
23 pairs on each side, 46 chromatids on either side.
What happens in telophase 1?
The number of chromosomes is now reduced by half. After this phase the cell is considered to be haploid.( only one set of chromosomes) Note however, that the chromosomes are still replicated, and the sister chromatids must still be separated during meiosis II.
In telophase 1, how many duplicated chromosomes are present? Sister chromatids?
23 chromosomes, 46 sister chromatids.
What happens in cytokenisis?
The cytoplasm and cell divide, resulting in haploid cells.
Are the chromosomes in cytokenisis duplicated or unduplicated?
Duplicated
Are tetrads present in cytokinesis
No.
Is there an interphase for meiosis II?
No
Why does meiosis II occur?
Because there is too much DNA in the haploid daughter cells
In prophase 2, how many duplicated chromosomes are present? Sister chromatids?
23, 46
How is prophase II different from prophase I?
Prophase II involves separation of sister chromatids, while prophase I involves the separation of homologous chromosomes.
How is the arrangement of chromosomes in metaphase II different than in metaphase I?
The chromosomes are no longer in tetrads
How is the arrangement of chromosomes in metaphase II different than in metaphase of mitosis?
The sister chromatids in metaphase II are crossed over.
In metaphase II, how many duplicated chromosomes are present? Sister chromatids?
23, 46
What happens in anaphase II?
The sister chromatids are finally separated.
How many duplicated chromosomes are present in anaphase II? Chromatids?
46 (23 either side), 0
How many haploid cells do the cells in telophase II divide into?
4
How many duplicated chromosomes are present in telophase II?
23 on each side
In the second cytokenisis of meiosis, how many chromosomes will be present in each resulting cell?
23
Are the resulting cells haploid or diploid?
Haploid
Are the chromosomes duplucated or unduplicated at the end of the second cytokenisis in meiosis?
Unduplicated
During which phase of meiosis are the homologous chromosomes separated?
Anaphase I
During which phase of meiosis are the sister chromatids separated?
Anaphase II
In a human cell, how many chromosomes does each daughter cell have after meiosis I?
23
In a human cell, how many chromosomes does each daughter cell have after meiosis II?
23
Describe why a person’s siblings are genetically different from one another?
Because of crossing over in prophase I.
What are three purposes of meiosis?
To replace diploid cells with haploid cells, to make gametes, and to create genetic variation.
What are other sources of genetic variation?
Mutation, independent assortment
What is nondisjunction?
When a pair of homologous chromosomes or sister chromatids fails to separate evenly during meiosis.
Can nondisjunction occur in meiosis I and II?
Yes
If nondisjunction occurs in meiosis I, how many gametes with abnormal chromosomes would result?
4 abnormal. (2 n+1, 2 n-1)
If nondisjunction occurs in meiosis II, how many gametes with abnormal chromosomes would result?
2 abnormal
What is monosomy?
When a cell is missing a copy.
What is trisomy?
When a cell has an extra copy
What is a karyotype?
A magnified image of chromosomes taken in homologous pairsand put in order.
Which phase is used for karyotyping and why?
Metaphase because it is the most clearly visualized.
What is aneuploidy?
Identifying an abnormal number of chromosomes.
What is Trisomy 21?
Down Syndrome. Extra chromosome 21, so a total of 47 chromosomes. Symptoms are lower cognition and facial differences.
What is Klinefelter syndrome?
When male has extra X chromosome. XXY. More feminine, more breast tissue, smaller testicles, and often sterile.
What is Turner Syndrome?
Females missing an X chromosome. XO. 45 chromosomes total. Webbed neck, heart problems, short stacked.
What are Metafemales?
When females have an extra X chromosome. XXX. Appear normal, might have low muscle deficiency and learning disabilities.
What is Jacobs Syndrome?
Supermale. Males have an extra Y chromosome. XYY. They are taller and more aggressive.
Explain how sexual reproduction can result in genetic diversity.
Because the zygote has half the genetic material from each parent
Explain the two main roles cell division plays in continuing life.
Growth and repair, and replacement of old cells.
Describe the process of binary fission.
Binary fission is the process bacteria use to replicate themselves. DNA replicates and cell membrane forms between the two chromosomes, dividing them and forming 2 daughter cells.
What factors in eukaryotic cells make cell division more complex than in prokaryotic cells?
The structure of the nuclear envelope in eukaryotic cells is more advanced.
Distinguish the difference between chromosomes, genes, and DNA.
Chromosomes carry DNA (condensed), genes are segments of DNA that give you physical characteristics, and DNA is your genetic blueprint.
How do sister chromatids attach to one another?
With a centromere
When in cell division, how do sister chromatids separate?
In anaphase, they are pulled to either end of the cell by spindle fibers.
Is the DNA in sister chromatids always identical?
Yes
Describe the phases and steps of the cell cycle leading to mitosis.
Before mitosis is the interphase, where DNA and organelles are duplicated and checkpoints are gone through to make sure the cell has the okay to carry out mitosis.
What must happen before cells can divide?
They must pass the checkpoints.
Describe cytokenisis.
Cytokinesis is when the cytoplasm separates in the 2 cells. Results in 2 diploid cells for mitosis, and 4 haploid cells in meiosis.
Define three main purposes for mitosis.
To grow and repair, replace old cells, and asexual reproduction.
Understand the stages of mitosis and what occurs at each phase.
Prophase: nuclear envelope disappearing, chromatin condensing into chromosomes, centrosomes moving to either end, spindle fiber formation.
Metaphase: sister chromatids move to center of cell on metaphase plate
Anaphase: centromeres broken, chromosomes move to either end of the cell.
Telophase: Clevage furrow emerges. Nuclear envelope reforming
Describe checkpoints. Where in the cell cycle do they occur?
Checkpoints are points within the cell cycle where the cell is checked to make sure it can undergo mitosis. G1 checkpoint happens before the S phase, G2 checkpoint happens before the mitotic phase, and M checkpoint happens before anaphase.
What role does mitosis play in cancer?
Cancer cells uncontrollably reproduce.
Describe homologous chromosome.
Homologous chromosomes are chromosome pairs. You get one from each parent, and they are similar but not identical.
Describe duplicated chromosome.
Duplicated chromosomes are when a single chromosome is duplicated and joined at the centromere. (identical)
Describe chromatid.
Chromatid is two identical chromosomes that split and contain the same genetic material.
Describe centromere
What holds together chromatids.
Describe tetrad
A paired set of homologous chromosomes, each containing 2 sister chromatids. (4 total)
Define the difference between autosome and sex chromosome.
Autosomal are chromosomes that are found in both men and women, and sex chromosomes are what determines the sex of offspring. (XX or XY).
Define diploid.
Diploid is a cell or organism that has paired chromosomes, one from each parent.
Define haploid.
When a cell has only one set of chromosomes.
Identify cells in humans that are haploid and diploid.
Diploid - somatic (body) cells. Haploid - gametes (sex cells)
Explain how mitosis and meiosis are different.
Mitosis produces genetically identical cells, whereas meiosis produces genetically diverse cells.
How many daughter cells does meiosis produce? Are they genetically identical?
Meiosis makes 4, and they are not identical.
Discuss events occuring during interphase of meiosis.
It is when there are checkpoints and DNA replication. Preparing the cell to divide.
Explain prophase I (synapsis, crossing over, formation of tetrads).
Prophase I is where homologous chromosomes pair up, tetrads form, crossing over (sharing DNA segments) happens.
Explain metaphase I
metaphase I is where tetrads line up on the center.
Explain anaphase I
When the tetrads are split and pulled to either end of the cell.
Explain telophase I
Chromosomes now reduced by half. Cell is now considered to be haploid. However, chromosomes are still replicated and sister chromatids need to be separated.
Explain prophase II
Each cell is haploid with chromosomes in replicated form
Explain metaphase II
Sister chromatids align in the center.
Explain anaphase II
Sister chromatids separated and pulled to either side
Explain telophase II
4 haploid cells starting to form, each with 23 chromosomes.
Cytokenisis II will result in how many daughter cells?
4 daughter cells.
Discuss the importance of crossing over.
It creates genetic variability in offspring.
Define nondisjunction.
Nondisjunction is an error of meiosis when a pair of homologous chromosomes or sister chromatids fails to separate evenly.
List some disorders that result from nondisjunction of chromosomes.
Trisomy 21, Jacob’s, Kleinfelter, Metafemale, Turner Syndrome
Discuss the major sources of genetic variation.
Mutation, crossing over, independent assortment.
If an organism has 16 total chromosomes (diploid), state the haploid number, number of chromosome pairs, and number of chromosomes found in the zygote.
Haploid - 8
Pairs - 8 pairs
Zygote - 16 chromosomes
Discuss the sources of genetic variation that occur in meiosis. Describe crossing over, orientation, mutation, and fertilization in your own words.
Independent assortment: where homologous chromosomes are randomly distributed to separate poles during meiosis.
Crossing over: when homologous chromosomes pair up and exchange DNA segments.
Dscribe the different chromosome abnormalities, including the chromosome types and symptoms.
Trisomy 21: extra chromosome on 21. Slow cognition, facial differences.
Kelinfelters: XXY. Males are more feminine, more breast tissue, small testicles, sterile.
Jacob’s: XYY. Males have extra Y. Taller, more aggressive.
Metafemale: XXX. Female has extra X. Low muscle deficiency, learning disability.
Turner: XO. Females missing and X. Webbed neck, short stature, heart problems. THE ONLY MONOSOMY (45 chromosomes)
