Meiosis, cell cycle, mendel and non mendelian, chromosomal Flashcards
What is the cell cycle
The life of a cell from its formation until it divides
allows for reproduction of cells, growth of cells, and tissue repair
What is the importance of the organization of DNA
cells must organize and package their DNA before division
Where is DNA organized
DNA associates with and wraps around protein known as histones to form nucleosomes
What does nucleosomes form
Chromatin
How does chromatin density change during cell division
When a cell is not actively dividing, chromatin is non-condensed form
After DNA replication, chromatin condenses to form a chromosome
Why are chromosomes densely packed
Chromosomes are densely packed to allow easier division
When DNA is replicated what happens to chromosomes
It is duplicated
What is the og chromosome and duplicated chromosome called
Sister chromatids
What is the centrosome
region of sister chromatid where they are most closely attached
what is kinetochore
protein attached to the centrosome that link each sister chromatid to mitotic spindle
What is a genome
all of the cells genetic information
What are prokaryotes
singular, circular DNA
What are eukaryotes
one or more linear chromosomes
Every eukaryotes have one specific number of chromosomes
Ex: Humans: 46, Chimps: 48, Elephants: 56
What are somatic cells
Body cells
Diploid (2n)
Divides by mitosis
Ex: Humans- 2n=46 (23 mom/23 dad)
What is a diploid
2 sets of chromosomes, one set from each parent
What are gametes
reproductive cells (egg/sperm)
Haploid (n)
Divide by meiosis
Ex: Humans- n=23
What is a haploid
one set of chromosomes
What are the phases of the cell cycle
Interphase (alternation), mitosis, cytokinesis
What is interphase
Longest protein of the cell cycle
1. G phase
2. S phase
3. G2 phase
What is G phase in interphase
First phase
Cell grows and carries out normal function
What is S phase in interphase
Synthesis phase
DNA replication and chromosome duplication occurs
What is G2 phase in interphase
Second gap phase
final growth and preparation for mitosis
What is M phase
Mitosis
Cytokinesis
Results in 2 identical diploid daughter cells
What is mitosis
nucleus divides
What is cytokinesis
cytoplasm divides
What are the 5 stages of mitosis
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase/Cytokinesis
What happens during prophase
Chromatin condenses
nucleoli disappears
duplicated chromosomes appear as sister chromatids
mitotic spindle begins to form
Centrosome moves away from each other
What happens during prometaphase
Nuclear envelope fragments
Microtubules enter nuclear area and some attach to kinetochores
What happens during metaphase
centrosomes are at opposite poles
chromosomes line up at metaphase plate
microtubules are attached to each kinetochore
What happens during anaphase
sister chromatids separate and move to opposite ends of cell due to the microtubule shortening
cell elongates
Define telophase and cytokinesis
Two daughter nuclei form
Nucleoli reappear
Chromosomes become less condensed
Cytokinesis occurs
What is different between plants and animals during cytokinesis
Animals: a cleavage furrow appears due to a contractile ring of actin filaments
Plants: vesicles produced by the Golgi travel to the middle of the cell and form a cell plate
What is “regulation of the cell cycle”
throughout the cell there are chromosomes
- Control points that regulate the cell cycle
- cell receives stop and go signals
What are the major checkpoints of regulation
1.G1
2.G0
3. G2
4. M (spindle)
What happens at the G1 checkpoint
most important checkpoint
checks for cell size, growth factors, and DNA damage
Stop: cell enter non-dividing state known as G0
Go: cell completes whole cycle
What happens during G0 checkpoint
Some cells stay in G0 forever (muscle/nerve cells)
Some cells can be called back into cell cycle
What happens during G2 checkpoint
Checks for completion of DNA replication and DNA damage
Stop: cell cycle stops and cell will attempt to repair damage
- if damage cannot be repaired the cell will undergo apoptosis (programmed cell death)
Go: cell proceeds to mitosis
What happens at M (spindle) checkpoint
Checks for microtubule attachment to chromosomes at kinetochores at metaphase
Stop: cell will pause mitosis at allow for spindles to finish attaching to chromosomes
Go: cell proceeds to complete mitosis and anaphase
What are internal cell cycle regulators
regulation of the cell cycle involves internal control system
1. Cyclins
2. Enzymes
What are cyclins
Proteins
synthesized and degraded at specific stages of the cell cycle
concentration varies
What are enzymes (in cell regulation)
Known as cyclin-dependent kinases (CDK)
active only when its specific cyclin is present and has specific regulatory effect
concentration remains constant throughout each phase of the cell cycle
What are external cell cycle regulators
growth factors
contact (density) inhibition
What is the growth factor of external cell cycle regulators
hormones released by cells that stimulate cell growth
-signal transduction pathway is initiated
- CDK are activated leading to progression through cell cycle
What is contact inhibition of external cell cycle regulators
cell surface receptors recognize contact with other cells
What is cancer and how does a cell become cancerous
evasion of the cell cycle
normal cells become cancerous through DNA mutations
What are DNA mutations
changes in the DNA
Cancer cells have on average accumulated 60 or more mutations on genes that regulate cell growth
What are Cancer cell traits compared to a normal cells traits
Do not follow checkpoints
divide infinitely
(considered immortal)
Evade cell death and continue dividing even with errors
If cancer cells infinitely divide and grow, what can this lead to
Tumor
What is a tumor and what are the types of tumors
Mass of tissue formed by abnormal cells
Benign tumor: cells are abnormal, but considered to be cancerous
- stay at site and are unable to spread anywhere else
Malignant tumor: mass of cancerous cell that lose their anchorage dependency that can leave tumor site
- metastasis
What are genetics
study of hereditary and heredity variation