Biology 112 Final Test Flashcards
What are the phases of the Eukaryotic Cell Cycle?
G1, G2, S, M
How much time does it take for the whole eukaryotic cell cycle?
24 hours
What is G1 and G2 phases of the cell cycle?
Gap phases
What is the S phase of the cell cycle?
DNA replication
How long does it take for S phase to do its job?
10 hours
What is the M phase in cell division?
Mitosis
How long does it take for M phase to do its job?
1 hour
What are the two big overall steps of DNA replication?
1) 2 parent strands are separated
2) Each parent strand is used as a TEMPLATE
In the first step of DNA replication, what is broken?
hydrogen bonds
How is DNA replication not transcription?
- more than 1 protein copied
- process is not to synthesize mRNA
- its semi-conservative`
Where does DNA replication begin?
origins of replication
Which direction does DNA proceed?
bidirectionally from the origin
How many start points are on each chromosome?
thousands
How many bases are needed each time the cell divides?
6 billion
What is a plasmid?
circular piece of DNA commonly found in bacteria
What is the rate of replication?
2000bp/minute (30ish per second)
How long would it take if there was only one origin of replication?
1 month
Why are origins of replication AT rich?
2 hydrogen bonds break easier than 3 of GC
What is ORC?
multi-subunit protein that binds at Origin to initiate replication
Which cells in the body are always replicating because of mechanical stress?
epithelial
What are enzymes that catalyze DNA replication?
DNA polymerases
Which direction of DNA does DNA polymerase work?
5’ to 3’
What is the problem of the direction DNA polymerase works?
DNA has two strands that are opposite directions
What is the strand that is made 5’ to 3’ called?
leading strand
What is the strand made 3’ to 5’ called?
lagging strand
How is the lagging strand made?
In fragments
DNA is not straight but spiral, what does this cause?
mechanical stress further down
What works to relieve the stress?
topoisomerase (gyrase)
How does the topoisomerase work?
Knicks/cuts one of two strands, unravel, then reconnect
What is a ligase?
an enzyme that will link okazaki fragments together
DNA Polymerases make mistakes…if not fixed what would happen
DNA would have mutations forever
What is the process of removing incorrect base and putting in correct base called?
proofreading
What are single stranded DNA binding proteins function?
single strand of DNA is susceptible and unstable and SSB gives protection and stability till nucleotides bond
What comes in to make short pieces of RNA to get DNA replication started?
primase
What binds the lagging strand parts?
ligase
What are ways DNA can be damaged?
carcinogens
What are carcinogens?
cancer causing agents
What is the process of DNA excision and repair?
1) enzymes recognize damage
2) damage is removed
3) Polymerase can fill in
4) DNA ligase does the rest
What is the outcome/ product of mitosis?
two identical daughter cells
What are the four stages of mitosis?
1) prophase
2) metaphase
3) anaphase
4) telophase
What happens in prophase?
- chromosomes condense
- centrosomes migrate
- mitotic spindle forms
- nuclear membrane fragments
What do chromosomes condense into?
compact fibers that are extensively folded
What forms the mitotic spindle?
microtubules from the centrosomes
What is the Kinetochore?
a protein complex attached to the chromosomes at centromere
What is Metaphase?
the point where prophase has occurred and chromosomes have been lined up but not yet separated
What is the metaphase plate?
the imaginary plane that is equidistant from the 2 poles of the spindle in which the chromosomes line up upon
When are chromosomes analyzed in lab?
metaphase
What occurs in anaphase?
sister chromatids are separated
How are the chromatids pulled?
microtubules getting shorter and shorter
What causes the microtubules to get shorter?
Small Motor proteins removing tubulin subunits from the microtubules
What is telophase?
the rebuilding of the cells
What is the final step in cell division?
cytokinesis
What is a contractile ring composed of?
actin and myosin
What is the product of meiosis?
four cells that ONLY contain one copy of each pair of homologous chromosomes
What are haploid cells?
only contain one pair of homologous chromosomes
What are homologous chromosomes?
similar but not exactly identical
What are alleles?
variations in genes
What are somatic cells?
non-germ cells, diploid, contain 46 chromosomes
What are germ cells?
haploid and contain only one set of chromosomes
How do haploid cells result in diploid state?
fertilization
How are Gametes formed?
process of meiosis
How many nuclear divisions are in meiosis?
two
How many daughter cells result of meiosis?
4
Are the 4 daughter cells of meiosis identical?
No, they are each genetically different
What is the key of meiosis?
homologous pairs line up in pairs and during 1st division sister chromatids stay together
What is the four stranded structure produced in lining of homologous chromosomes?
bivalent
What occurs in the first division during Meiosis I?
homologous chromosomes are separated from each other and two cells are formed
What occurs in the second division during Meiosis II?
The sister chromatids line up and are separated resulting in 4 cells of 23 chromosomes
What occurs in meiosis that lends towards more genetic diversity?
chromatids of homologous chromosomes exchange DNA
Why is only one egg formed in female?
uneven distribution of cytopasm results in only one function
What is the probability of conceiving genetically identical children?
1 in 64 trillion
Why do cells need to communicate with each other?
behavior of cells throughout body should be coordinated
What do cells make up that affect communication?
cells make up tissues that make up organs that then should be regulated by cell activity
What is one thing, other than organelles, that each cell has?
genome
What is genome?
have all genes/DNA
Are all genomes expressed?
No, only the genes needed for function of the cells
What is gene expression regulated by?
transcription factors
What is a huge end result of expression and communication?
regulation of genes
What are transcription factors often regulated by?
signaling pathways
What does signaling pathway ultimately end with?
signaling factors
What is apoptosis?
No signaling or a signal tells it to go away, DNA self destruction
What is the process of signaling?
1) receptor-ligand binding
2) signal transuction
3) cellular responses
4) changes in gene expression
Are the receptors specific or general?
specific to protein
What does it mean that signal transduction pathways can amplify?
the cell pathways are not 1:1 and amplify and activate other cells so the signal gets bigger and bigger
What are the two types of signaling
Homonal
Local mediators
What is homone signaling?
distant cell that binds to a target cell at some distance away
What is local mediator signaling?
cell is communicating with the cells adjacent or close to it
ex: nervous system
What types of cells can pass through a membrane and directly bind to intracellular targets?
steroids
What are the two types of cell-surface receptors?
1) G-protein linked
2) enzyme-linked recptors
What is the g stand for in g linked receptors?
guanine
What is the largest class of cell-surface receptors?
g-protein
What type of cells is g-protein found?
eukaryotes
What do G-protein linked receptors consist of?
single polypeptide chains
7-membrane spanning domains
What is the function of G-protein linked receptors?
binding of signal molecule causes conformational change activates a G-protein
What are G-proteins?
GTPases
How is the inactivated binded GDP activated?
when it binds GTP it releases alpha unit and becomes activated that can activate other proteins
Is the signal of G-protein temporary or lasting?
temporary
What ends the signal of G-protein?
GTPase breaks down to GDP which ends signaling pathway
What is enzyme linked receptors?
single-pass transmembrane proteins
What is the function of enzyme-linked receptors?
bind signal molecules
How fast is the enzyme linked receptor?
slow (hours)
Cystosolic domain is either an enzyme itself OR associated directly with an enzyme…
INFO
Receptor Tyrosine Kinases outside function.
binding receptor inside= phosphorylating things
How are receptor tyrosine kinases activated?
dimerization following binding of signaling molecule
what is autophosphorylation?
monomers phosphorylate each other
What do phosphorylated tyrosines serve as?
binding sites for other signaling proteins
What is carcinoma?
cancers arising from epithelial cells
Why is epithelial most common?
deal with most mechanical stress and need duplication the most
What are 2 main characteristics of cancer cells?
1) uncontrolled growth
2) ability to spread
What are 6 results of uncontrolled growth?
1) anchorage independent growth
2) lose contact inhibition
3) abnormalities in signaling pathways
4) disruptions in cell cycle control
5) block of apoptosis
6) balance of replication/differentiation is shifted
What is apoptosis?
programmed cell death
Does cancer occur at one mutation?
No, it is the accumulation of mutations over a lifetime
What occurs when balance of differentiation is disrupted?
tumors occur, build up of cells
Why does apoptosis occur?
health of entire organism is more important than any single cell
What are two forms of cell death?
1) apoptosis
2) necrosis
What is necrosis?
cell bursts and contents spill out
How does necrosis result?
1) injury
2) inflammatory response
How does apoptosis process occur?
1) cell condenses and shrinks
2) cell surface changes to cause endocytosis by macrophage
3) chromosomal DNA is cleaved
How does apoptosis and cancer relate?
If process is mutated
What is the difference between benign and malignant tumors?
ability to spread
What is a benign tumor?
single mass of cells that have not invaded surrounding tissue
What is malignant tumor?
cells have acquired ability to invade surrounding tissue
What is metastases?
cells can break off from primary tumor, enter the bloodstream, and form secondary tumors at other sites
For the ability to spread what do tumors need?
Angiogenesis
Invasion
Metastasis
What is angiogenesis?
new blood vessel formation
Without angiogenesis how large can tumors grow?
1-2mm
What initiates angiogenesis?
VEGF to bind to blood vessels and initiate growth
What is invasion?
direct migration into neighboring tissues
What do cancer cells release that destroys protein barrier?
proteases enzymes
Where do cancers metastasize/ why?
Lymph nodes: before entering bloodstream, many cancer cells enter lymphatic vessels and are carried to lymph nodes to blood stream
Once tumors in bloodstream where do they usually go?
Lungs: tumors in most organs encounter capillary bed of the lungs when they enter blood stream
Liver: cancers arising in stomach and colon cells enter the liver shortly after entering bloodstream
What are the two factors that cause cancer?
Hereditary
Environmental
What are chemicals that cause cancer called?
carcinogens
What do carcinogens often cause?
DNA mutations
What other factors cause DNA mutations?
UV light and radiation, viruses
How many mutations are needed in order for a cell to be cancerous?
6-10 mutations
What two specific genes are mutated by carcinogens and radiation?
1) Oncogenes
2) tumor suppressors
What are oncogenes?
tell the cell when to duplicate and promote growth in cells under normal circumstances
What are tumor suppressors?
tells the genes when to stop duplication
What occurs when oncogenes are expressed at higher levels?
cancer, over growth of cell
What occurs when tumor suppressors lose function of being turned off or non-functional?
cancer
What is chemotherapy?
anti-cancer drugs that kill rapidly growing cells
