Cycle 2 (Workshop and Study Session) Flashcards
Explain difference between prokaryotes vs. eukaryotes
Prokaryotes: DNA is in nucleoid, replication occurs through binary fission
Eukaryotes: DNA is in nucleus, replication through mitosis and meiosis
Step 1 of Binary Fission
Prokaryotic parent cell initiates replication
Step 2 of Binary Fission
A copy of the cell’s DNA is created
Step 3 of Binary Fission
Cell elongates and cross wall forms
Step 4 of Binary Fission
Cross wall forms completely and daughter cells separate
Define:
Mitosis
Cell division into 2 identical daughter cells
What are the phases of a eukaryotic cell cycle?
Interphase (G0, G1, S, G2), Mitosis (Prophase, Prometaphase, Metaphase, Anaphase, Telophase)
What happens in G1?
Cell growth and differentiation
What happens in S?
DNA Replication
What happens in G2?
Preparation for Mitosis
What happens in prophase of mitosis?
Chromosomes condense and pair up
What happens in prometaphase of mitosis?
Nuclear envelope breaks down, bundles of spindle microtubules grow from centrosomes at spindle poles towards cell centre
What happens in metaphase of mitosis?
Spindles reach final form, chromosomes line up at the spindle midpoint
What happens in anaphase of mitosis?
Sister chromatids are pulled apart to opposite spindle poles
What happens in telophase/cytokinesis of mitosis?
Spindle disassembles, chromosomes at each spindle pole decondense, cell pinches in the middle
Altogether, two identical daughter cells are formed
Why is cell division necessary?
Tissue Repair
Multi-Cellular Growth
Regeneration
Maintain high Surface area : Volume Ratio
Why do cells need to maintain a high surface area to volume ratio?
At a large volume, surface area cannot keep up with the demands of the cell
Thus cell must divide to survive
What are the cell cycle checkpoints?
G1/S
G2/M
Mitotic Spindle
What does G1/S checkpoint assess for?
Cell size and DNA damage
What is required for cell to continue through G1/S checkpoint?
Growth factor presence required to enter synthesis (S stage)
What does G2/M checkpoint assess for?
Proper chromosomal replication
DNA Damage
What is required for cell to continue through G2/M checkpoint?
Molecules required to enter mitosis
What does Mitotic Spindle checkpoint assess for?
Attachment of spindles at kinetochores
Chromosomes are lined up evenly on metaphase plate
What does the Mitotic Spindle checkpoint mitigate?
Aneuploidy
Define:
Aneuploidy
Abnormal number of chromosomes
Define and give examples of:
Positive Regulators
Regulators that induces cell cycle
Cyclins and CDK
What are cyclins?
Cyclins binds to CDK to form Cyclin-CDK complex
What is CDK?
Phosphorylation cascade intermediate
Define and give examples of:
Negative Regulators
Negative regulators halts the cell cycle
p53 and p21
How does p53 work?
Detects damage and upregulates p21 transcription
How does p21 work?
Binds to CDK to inhibit Cyclin-CDK complex
How does normal p53 differ from mutated p53?
Normal p53 is the Guardian of the Genome
If DNA damage, cell cycle abnormalities, or hypoxia occurs, it will arrest the cell cycle and either undergo DNA repair and restart, or apoptosis
Mutate p53 will not respond to DNA damage, cell cycle abnormalities, or hypoxia
Thus, the cell cycle continues and the cells become cancerous
Define:
Apoptosis
Programmed cell death
How are chromosomes counted?
One chromosome = One centromere
True or False:
Sister chromosomes are identical
Depends. Sister chromatids are identical before recombination
True or False:
Homologous chromosomes are identical
False, homologous chromosomes are related but not identical
Define:
Meiosis
Cell division into 4 unique daughter cells
What happens in prophase I of meiosis?
Chromosomes condense and pair up
True or False:
Meiosis I is reductional
True
Describe Meiosis I
Homologous chromosomes separate
The number of chromosomes is halved
The cells produced are now haploid
True or False:
Meiosis II is reductional
False, meiosis II is equational
Describe meiosis II
Sister chromatids separate
The number of chromosomes is unchanged
Similar to mitosis
Define:
Recombination
Swapping chromosome segments in prophase I of meiosis
Alleles on the same chromosome are ____ likely to end up together
More
The closer that alleles are, the _____ the chance recombination will _______ them
Lower
Separate
Lists ways of to create variation in meiosis
Homologous Recombination
Independent Assortment
Random Alignment
Random Fertilization
Explain Independent Assortment
Chromosomes segregate independent of one another (anaphase)
Explain Random Alignment
Chromosomes line up at metaphase plate randomly (metaphase)
______________ causes Aneuploidy
Nondisjunction
Life cycle of an animal:
Gametes undergo _______
Zygotes undergo _______
Meiosis
Mitosis
Life cycles of plants and most fungi:
Gametes undergo _______
Spores undergo _______
Mitosis
Meiosis
Life cycles of algae and some fungi:
Gametes undergo _______
Zygotes undergo _______
Mitosis
Meiosis