Molecular Reproduction Flashcards
What are the four stages of the cell cycle in order?
G1 (G0)
S
G2
M
Describe interphase
Made up of stages G1, S and G2. Is the longest portion of the cell cycle, with cells spending 90% of their time there
What is G0 stage?
An offshoot of the G1 stage where cells are simply living and carrying functions as normal and not dividing
Describe G1 stage
aka “presynthetic gap”. Cells increase size and rate organelles for energy and protein production
What must cells do to pass from G1 to S stage?
Go through a restriction point that contains criteria like having a full complement of DNA before entering S stage
Describe S stage
aka “Synthesis of DNA”. Cell replicates its genetic material to have copies and gets two identical chromatids bound together by a centromere
Describe G2 stage (CHANGE ANSWER)
aka “postsynthetic gap” cell has another quality checkpoint in which the cell ensures that their are enough organelles and cytoplasm for two cells. Also checks to make sure the cell DNA got replicated properly without mistakes
Describe M stage
aka “Mitosis” cell ungoes mitosis stages and cytokinesis
What are the checkpoints the cell must go through in the cell cycle?
First one - between G1 and S to make sure their is a full complement of DNA and it’s good before proceeding to S, aka “restriction point”
Second one - in between G2 and M which ensures there is enough organelles and cytoplasm to divide along with correct DNA
What is p53?
the main protein that controls the G1/S restriction point that makes sure DNA is not damaged and gets repaired
How to cyclins and CDKs work in the cell cycle? NEED MORE INFO IN ANSWER
CDKs are activated by the presence of cyclins that increase or decrease in concentration during certain parts of the cycle. CKDs and cyclins form a complex that can phosphorylate transcription factors that promote genes being transcribed for the next part of the cell cycle
What is one of the most common mutations that cause cancer?
A mutation in the TP53 gene that encodes for the restriction point protein p53 will stop that protein from checking for damaged DNA and therefore the bad DNA gets replicated into new cells
What is the definition of mitosis?
the process by which two identical daughter cells are created from a single cell
What is a somatic cell?
any cell not involved in reproduction
What are the phases of mitosis in order?
Prophase, Metaphase, Anaphase, Telophase and Cytokinesis
Describe prophase
First phase of mitosis. Chromatin gets condensed into chromosomes, centrioles pairs separate and move towards opposite poles of the cell, the cell forms spindle fibers, the membrane dissolves,
Describe metaphase
Second phase of mitosis. Centriole pairs are now at opposite ends of the cell. Kinetochore fibers align the chromosomes at the metaphase plate
Describe anaphase
Third phase of mitosis. Sister chromatids are pulled apart by shortening kinetochores
Describe telephase
Fourth phase of mitosis. “Opposite of prophase”. spindle apparatus disappears , nuclear membrane reforms, chromosomes uncoil
Describe cytokinesis
Fifth phase of mitosis. Separation of the cytoplasm and organelles.
What is reductional division vs equational division?
Reductional division is when you get haploid cells and equational division is when you get diploid cells
What is meiosis?
A division process that create four cells through two divisions to create gametocytes
What are the stages of meiosis?
Meiosis I (Including Prophase I, Metaphase I, Anaphase I, Telophase I) Meiosis II (Including Prophase II, Metaphase II, Anaphase II, Telophase II)
What is synapsis?
When homologous chromosomes come together and intertwine
Describe how Meiosis works
The first round is when homologous chromosomes cross over during prophase I and the rest of the cycle is spent splitting the cell apart so that each cell now has one homologous chromosome of each kind. The next round splits the sister chromatids and now four unique cells are made.
What is the difference between chromosomes and chromatids and chromatin?
Chromatin - made of DNA and histones in thin stringy fibers
Chromosomes - condensed version of chromatin which are single stranded. Becomes X shaped after replication
Chromatid - either of the two strands of a replicated chromosome that form the X. If connected by centromere they are called “sister” chromatids
