The Cell Cycle Flashcards
What is cell division?
reproduction of cells. There are two types: mitosis and meiosis
What is a genome?
a cell’s DNA or genetic information
What is a chromosome?
One chromosome is made of DNA and proteins called histones.
DNA is packaged this way so that all of the DNA can fit in the eukaryotic cell.
What is chromatin? How does it differ from a chromosome?
Chromatin is DNA and proteins but is spread out/not as tightly packed as a chromosome.
Same material, but different format.
What is a somatic cell?
All the cells in the body except for sperm and egg.
A human somatic cell has 46 chromosomes.
What is a gamete?
egg or sperm
A human egg or sperm contains 23 chromosomes.
The number does NOT indicate complexity as a somatic cell of algae has 148 chromosomes!
what is a sister chromatid?
copies of the original chromosome (after S) joined by cohesions.
Each chromatid has a centromere-region made of repetitive sequences of DNA where the chromatid is most tightly attached to its sister chromatid.
Proteins recognize the DNA sequences, bind or help DNA condense.
What is cytokinesis?
division of the cytoplasm
It is different in plant and animal cells, due to a plant having a cell wall.
What is the M phase?
M phase (the shortest part of cell cycle) is made up of MItosis (division of genetic material in the nucleus) and cytokinesis (division of the cytoplasm)
what is interphase?
90% of cell cycle
Made up of G1, S, and G2
What happens during prophase?
A Key to prophase is seeing the chromatin tightly coiling. You can see this with a light microscope.
What happens during prometaphase?
A Key is kinetochore. This is formed at the centromere of each chromatid. This is where spindle fibers attach. Not all spindle fibers attach to a kinetochore.
The nuclear membrane disappears.
What happens during metaphase?
Chromosomes have arrived at the metaphase plate.
Kinetochores of the sister chromatids are attached to the kinetochore microtubules.
What happens during anaphase?
Shortest phase
Cohesion proteins are cleaved by separase
Kinetochore microtubules shorten and pull on centromeres
Chromosomes are pulled to the poles
What kind of inhibitor is securin?
What happens during telophase?
Two daughter nuclei form
nucleoli reappear
chromosomes become less condensed
spindle is depolymerized
mitosis is over!
How do kinetochore microtubules function during anaphase?
What is the function of the cell plate?
A cell plate helps to divide plant cells.
There is no cleavage furrow due to the cell wall.
What is binary fission?
Asexual reproduction in single-celled eukaryotes and prokaryotes.
What is a checkpoint?
control point where stop and go-ahead signals can regulate the cell cycle.
Which gene controls the checkpoint in G1?
There is also a checkpoint in S.
Which gene controls it? What it is checking for?
Which enzyme is activated as a result of all the kinetochores are attached to the spindle?
What is a growth factor? What is an example?
a protein released by certain cells that stimulate other cells to divide
ex. PDGF
What would happen if PDGF was not present at the site of a wound?
What is density-dependent inhibition?
crowded cells stop dividing
This happens because cell surface proteins on one cell binds to one on another cell. A signal is sent to stop cell division.
Cancer cells ignore this!
What is anchorage dependence?
To divide, cells must be attached to something such as a flask or petri dish or the extracellular matrix.
Cancer cells ignore this!
What is a benign tumor?
mass of abnormal cells that remains at the original site
What is a malignant tumor?
Cells that have genetic changes that allow them to spread to new tissues.
The tumor impairs the functions of one or more organs.
The spread is called metastasis.
What are the parts of the cell cycle?
G0, G1, S, G2 and M
What happens in each stage?
What are the relative lengths of each phase?
M is divided into Mitosis and Cytokinesis.
What is a gene?
hereditary unit
segment of DNA
passed to offspring by parents
What is a gamete?
Where are they made in humans?
Are gametes haploid (n) or diploid (2n)?
reproductive cells
egg (ovary)
Sperm (testes)
haploid
What is the haploid number of human sperm? egg?
23 chromosomes
What are somatic cells?
All cells of the human body except for gametes
ex. skin cell, muscle cell, neuron
What is asexual reproduction?
An individual is the sole parent and passes copies of all its genes to its offpsring without fusion of gametes.
What is sexual reproduction?
two parents give rise to offspring
A unique combination of genes.
Not clones!
Genetic variation!
What is a karyotype?
images of chromosomes are arranged in pairs in a specific way.
The longest chromosomes start first, ending with the sex chromosomes.
The first 22 pairs are called autosomes.
Note: the notation of the karyotype. 47 XY +18
What would the notation be for this karyotype?
47 XXY
This is Klinefelter Syndrome
What is a zygote?
fertilized egg formed by the fusion of an egg and sperm nuclei.
What are homologous chromosomes?
both chromosomes of a pair carry genes controlling the same inherited characteristic.
Same length, centromere position, and staining pattern
The image shows a pair with three genes.
What is meiosis?
The type of cell division that forms gametes
crossing over
DNA molecules of non-sister chromatids are broken and are rejoined to each other.
This happens in Prophase I.
At least one crossover must take place to keep the homologous pair together.
chiasmata
points of attachment where crossover occurred
independent assortment
generates genetic variation
the orientation of homologous pair
223 combinations of chromosomes in the formation of human gametes
Recombinant chromosomes
individual chromosomes that carry DNA from two different parents
Random fertilization
the fusion of male and female gametes to produce a zygote with
223 X 223 diploid combinations = an incredible amount of variation!
