pdbio exam 4 Flashcards
In order for cells to grow they ____.
divide
As cells divide, genetic material (chromosomes) must be carefully duplicated, sorted and a copy passed to a new cell. The process whereby this occurs is called ____.
mitosis
Prokaryotes pass on their genetic information through ____.
Binary fission - dan replicates, moves to ends of cells, and cell pinches off into two.
Before a cell is dividing the DNA is found in the form of ____. Before replication the ____ condenses to form ____.
chromatin
chromatin
chromosomes
Chromosomes are made up of 3 things:
DNA, RNA, and protein
When a chromosome is duplicated and linked with its duplicate, the two pairs are known as ____.
sister chromatids
Mitosis involves the separation of the ____.
sister chromatids
The constriction point holding sister chromatids together is called the ____.
centromere
Whether in the x structure or the single structure, it is still called a ____.
chromosome
Humans have ____ pairs of chromosomes. (____ total chromosomes).
23 pairs
46 total
The 23 chromosomes from mom and the 23 chromosomes from dad are called _____ chromosomes.
Homologous
The 22 pairs of chromosomes in humans are called ____. The 23rd pair (xx or xy) is called ____.
22 autosomal pairs
1 pair of sex chromosomes
Diploid number
2n (two of each chromosome)
____ is a set of events for cell growth and division.
Cell cycle
The cell cycle is divided into 2 main sections:
interphase and mitotic (M) phase
3 parts of interphase
G1, S phase, G2 phase
What makes up the M phase?
mitosis and citokinesis
The majority of the cells life is spent in ____.
interphase
What happens during the G1 phase?
How many chromosomes are there in a human cell during the G1 phase?
- cell growth
- signaling molecules can cause cell to accumulate molecular changes that promote progression through the cycle
- if the cell passes the restriction point, or G1 checkpoint, the cell becomes committed to enter into S phase
- 46 chromosomes
What happens during S phase?
- chromosomes replicate
- after replication, two copies stay joined to each other and are called sister chromatids
What happens in the G2 phase?
How many chromosomes are there in a human cell during the G2 phase?
- cell synthesizes proteins needed for mitosis and cytokinesis
- 46 pairs of sister chromatids and 92 chromatids total
The decision of one cell nucleus into two, with separation of sister chromatids is what?
mitosis
Follows mitosis to divide the cytoplasm into two daughter cells?
cytokinesis
What determines the decision to divide?
External factors: -environmental conditions -signaling molecules Internal factors: -cell cycle control molecules -checkpoints
Proteins responsible for advancing a cell through the phases of the cell cycle
Cyclins or “cdks”
`What are the three checkpoints?
G1 checkpoint (restriction point) G2 checkpoint Metaphase checkpoint
Checkpoint proteins are ____ to determine if the cell is in proper condition to divide.
sensors
Loss of checkpoints can lead to what ?
mutations and cancer
In mitotic cell division, the cell divides to produce two new cells that are _____ to the original.
genetically identical
The original cell is called the _____ and the two new cells are called the _____.
mother cell
daughter cells
What is the way to remember the phases of mitosis?
PPMAT
What happens during interphase?
chromosomes are replicated
What happens during prophase?
chromosomes start to condense, mitotic spindle starts to form, nuclear envelope begins to dissociate.
What happens during prometaphase?
nuclear envelope is completely dissociated, mitotic spindle fully formed. Spindles attach to kinetochores on chromosomes.
What happens during metaphase?
sister chromatids along along metaphase plate
What happens during anaphase?
sister chromatids separate, and individual chromosomes move toward poles
What happens during telophase and cytokinesis?
nuclear envelope reforms. Cytokinesis separates mother cell into two daughter cells.
Chromosomes that are not sex chromosomes are called ____.
autosomes
In diploid cells, eukaryotic chromosomes occur in _____.
homologous pairs
Geneticists use the letter ____ to represent a set of chromosomes.
n
the gametes are the ___ and ___ cells.
sperm & egg cells
Cells, such as gametes, that contain one set of chromosomes are called ____ cells.
haploid
Cells of a human being have ____ chromosomes each because the person obtained one set from both mother and father.
46
In a diploid organism, a pair of chromosomes consists of two ____.
homologs.
How many chromosomes does a human gamete possess?
23
Bivalent formation and crossing over are two key events that typically occur at the beginning of what?
meiosis
Meiosis I sorting separates what?
homologous chromosomes
List the phases of meiosis in the correct order:
prophase, metaphase, anaphase, telophase (and cytokinesis)
T or F: sister chromatids are separated during mitosis and meiosis.
True
In what phase of meiosis are sister chromatids separated?
anaphase II
What is a pulse-chase experiment
1) pulse: labeling of a certain part of the cell
2) chase: essentially watching what happens to the label after a certain period of time
Meiosis only happens in the ___.
gametes
During sexual reproduction, a sperm and an egg unite to form a new individual. This is called ____.
fertilization
What is the nuclear division that precedes the formation of gametes?
meiosis
Meiosis reduces the chromosome # by ____. In diploid organisms, the products of meiosis are ____.
half
haploid
In meiosis the parent cell contains a ______ pair of chromosomes. It is a ____ cell.
homologous
diploid
Homologs carry the same genes in the same locations, but each one may contain different ____.
alleles
Mitosis produces two ____ daughter cells that are genetically identical. Meiosis produces four ____ daughter cells.
diploid
haploid
In what phase of meiosis does crossing over occur?
Prophase I
What happens in prophase I?
homologous pairs of chromosomes match up
What happens in metaphase I?
homologous pairs are lined up next to each other, and homologous pairs are lined up end to end.
What happens in anaphase I?
homologous chromosomes are pulled apart but sister chromatids remain intact.
When the cell divides after meiosis I, each cell now has ____ the # of chromosomes as the parent cell, and each chromosomes still has _____.
half
sister chromatids
What happens in metaphase II?
all the chromosomes line up end to end
What happens in anaphase II?
the sister chromatids are pulled apart, resulting in the same # of chromosomes in each daughter cell as at the beginning of meiosis II.
The fundamental purpose of meiosis is to…
make a gamete
Crossing over produces what?
increased genetic variation
A definition of haploid might be:
a cell that contains only one set of chromosomes
If you inject the cytoplasm of a cell currently in M-phase of the cell into an oocyte (undeveloped egg cell) not currently in M-phase, the oocyte will be triggered to enter mitosis. What would you predict would happen if the cytoplasm from a G2 phase cell were injected into an M-phase cell?
mitosis would immediately stop.
While working in a soil ecology lab, you discover a bacteria that seems to replicate in an odd manner. You begin to film a single cell and notice that when it is about to divide, homologous chromosomes are not paired, and it doesn’t appear that any crossing over or other DNA recombination events occurred. Is this cell dividing using a mitotic or meiotic process?
mitosis
Genetic variation ism needed to allow an organism to adapt to changing environments. Incest increases the risk of diseases due to the decreased variation in the genome. Which of the following processes would help create genetic variation?
independent assortment, crossing over, mutations
What is the genetic makeup of an organism? (ex: BB)
genotype
What is the effect of gene expression on the whole organisms?
phenotype
What is the alternative form of a gene?
allele
What is the place where a gene is found along a chromosome?
locus
When an individual has two fo the same allele at a locus, or across all of its loci it is called…
homozygous
When an individual has different alleles at a locus, or at all of its loci where its two parents differed it is called…
heterozygous.
When an allele is expressed even tho its heterozygous…
dominant
When an allele is not expressed unless it is homozygous
recessive
Gregor Mendel performed experiments with
pea plants
Two different lines are crossed reciprocally
reciprocal crosses
What are Mendel’s three important ideas?
- genes and alleles - every individual has two “unit factors” (genes) for a character and an individual has two variants (alleles) of each gene.
- traits are dominant and recessive
- segregation of alleles - two copies of a gene carried by an F1 plant segregate from each other, so that each sperm or egg carries only one allele
What is Mendel’s law of segregation?
two copies of a gene segregate from each other during the transmission from parent to offspring
What is Mendel’s law of independent assortment?
alleles of different genes assort independently from each other during gamete formation
-assumes no crossing over
The possible number of different gametes produced is ____ where n is the number of heterozygous traits
2n
Genes found exclusively on the X chromosome are called?
x-linked
Who is considered to be the Father of Genetics?
Gregor Mendel
Pure lines crossed always produce _____.
uniform progeny!
What are the 3 deviations from Mendel’s laws?
- Incomplete Dominance - A single allele doesn’t produce a sufficient quantity of enzyme and the F1 phenotype is intermediate (ex: pink flower from red and white flower)
- Codominance - offspring expresses both the “dominant” and the “recessive” traits (ex: a pink and white spotted flower)
- Polygenic (Quantitative) Inheritance - phenotypes are a result of multiple genes. As a result, there are many different possibilities for these traits. (ex: hair color)
Sex chromosomes pair at ______ as if they were homologues.
meiosis I
The ____ determines the sex of the offspring
father
In humans, the ___ chromosome is larger than the ___ chromosome and carries more genes.
X is larger than the Y
Males are ____ for x-linked traits
hemizygous
Chromosomes can be mapped based on recombination frequencies between loci. This theory is called…
the Chromosome Theory of Inheritance
Genes that are close together on a chromosome are ____ likely to undergo recombination. They will have a ____ recombination frequency, meaning they are usually passed down together.
less
low
When two genes are located close to one another on a chromosomes, they tend to be transmitted together. This phenomenon is known as ?
linkage
The exception to Mendel’s law of independent assortment is
when two genes are linked (on the same chromosome)
The way linked genes can be passed down independently is if ____ occurs
crossing over
A chi-square statistic is a ____ analysis
quantitative (using numerical data)
What is the null hypothesis in a genetic experiment using x2?
THE OBSERVED OFFSPRING WILL MATCH THOSE EXPECTED WITH INDEPENDENT ASSORTMENT (FOLLOW MENDELIAN RATIOS ACCORDING TO THE PUNNET SQUARE)
