VCU Exam 2 Flashcards
cell division purpose
growth, maintenance (cell regeneration), repair, reproduction (sexual-meisosis, asexual-mitosis)
binary fission
prokaryote cell division, elongation of plasma membrane until cell walls form. produce 2 identical daughter cells
cell cycle
interphase (G1, S-DNA synthesis, G2), M phase (cell division-mitosis), cytokinesis (actual separation into 2 cells)
somatic cells
all cells in the body except for sperm and egg. 46 chromosomes (23 each from mom and dad)
ploidy
sets of chromosomes.
Somatic-diploid (2n)
Gametes/sex cells- haploid (1n)
Polyploidy- Xn (ex: 28n)
chromatin
loosly unwound and decondensed DNA with associated proteins
sister chromatids
2 identical copies formed by the replication of a single chromosome (either maternal or paternal)
centromere
made of proteins, hold the sister chromatids together
M phase
4 subphases (prophase, metaphase, anaphase, telophase) PMAT
contractile ring
composed of microfilaments-made out of actin. present in at the end of telophase, starting cytokinesis
homologous chromosomes
22 pairs (carrying the same genes), the rest are sex chromosomes
associated proteins of DNA
help the DNA form tight coils and replicate to form sister chromatids
Mitosis
1 cell divides into 2 identical daughter cells. No change in ploidy
Mitosis prophase
most complex and longest, occurs after interphase
DNA is in chromatin form, condenses into chromosomes
spindle apparatus forms each moving towards opposite poles of the cell
Nuclear envelope breaks down, sister chromatids can move freely within the cell
Microtubules from the spindle apparatus extend and attach to chromosomes (fully condensed) at the kinetochore.
Non-kinetochore microtubules extend to expand the cell
Mitosis metaphase
chromosomes line up at the metaphase plate (middle of the cell) while still connected with the microtubules
Mitosis anaphase
sister chromatids pulled apart to opposite sides of the cell by microtubules
Mitosis telophase
the nuclear envelope reforms around both sides of the chromosomes. DNA decondenses into chromatin
Mitosis cytokinesis
starts during telophase, the process of cells splitting in 2. Contractile ring forms until they pinch off into 2 cells
Mitosis in plants
everything is the same except for cytokinesis. The plasma membrane split instead of cleavage furrow forming, and cell wall develops
phragmoplast
overlapping microtubules that guide vesicles containing cell wall components to the middle of the cell
Meiosis
division of germ cells. produce gametes: sperm or egg. Start with 1 cell to produce 4 non-identical daughter cells. Ploidy cut in half.
Meiosis prophase I
chromatin condenses into chromosomes,
sister chromatids join at centromere forming homologs
nuclear envelope breaks down.
spindle apparatus moves towards opposite poles
synapsis and crossing over occurs
microtubules attach at kinetochore, or not to expand cell
synapsis
homologous chromosomes join together forming a bivalent/tetrad
crossing over
occurs at the chiasma, a form of genetic recombination to increase genetic variation
Meiosis metaphase I
homologs line up at the metaphase plate at random orientation (genetic recombination-add to variety)
Meiosis anaphase I
homologs separate
Meiosis telophase I
nuclear envelope forms around DNA,
DNA uncoils back to chromatin
Meiosis cytokinesis
cleavage furrow forms, producing 2 non-identical (because of genetic recombination) haploid cells (2n)
Meiosis II
start with the product of meiosis I (2 haploid non-identical daughter cells), produces 4 non-identical daughter cells (1n) aside from prophase all the rest of the phases are like mitosis
Meiosis prophase II
similar to prophase of mitosis (only sister chromatids) not homologs like prophase I
Genetic recombination
contribute to genetic variation, crossing over in prophase I, line up orientation in metaphase I, random line up orientation in metaphase II
CDKs
cyclin dependent kinase, regulate cell cycle by phosphorylation (adding a phosphate group)
cyclin
activate CDKs (on its own is inactive), cycle in abundance
G1/S cyclin/CDK complex
promote the expression of histone proteins (help chromatin to condense into chromosomes)
S cyclin/CDK complex
specific to S phase, promote the proteins needed in DNA replication and proteins that prevent DNA re-replication
M cyclin/CDK complex
promotes proteins involved in mitosis (break down the nuclear envelope), and tubulin proteins (microtubules formation)
G1 checkpoint
towards the end of G1. is the DNA damaged? if so, it promotes the expression of G1/S cyclin/CDK complex inhibitors (kinase comes and phosphorylate) so the cell cycle cannot progress
G2 checkpoint
towards the end of G2. Has all the DNA been replicated?
M checkpoint
occurs during anaphase. Are all the kinetochores attached to the microtubules?
cancer
uncontrolled rapid cell division, caused by oncogenes, series of mutations (usually 4 before cancer occurs), turn on proto-oncogenes and turn off tumor suppressor genes
proto-oncogenes
genes involved in promoting cell cycle, normal for repair and cell division. Can get out of control and become oncogenes
tumor suppressor genes
inhibits the cell cycle, prevent unneeded cell division, puts cell into G0- nondividing state
phototrophs
get energy directly from the sun
autotrophs
get carbon from CO2. Photoautotrophs- plants
heterotrophs
get carbon from organic compounds. Photoheterotrophs- some bacteria and single celled organisms
chemotrophs
get energy from a chemical compound, can be autotrophs or heterotrophs. Humans are chemoheterotrophs
metabolism
sum of all chemical reactions within an organism
catabolic pathway
series of chemical reactions that start with large molecules and breaking them down into small molecules. Net release of energy (ex: cellular respiration)
anabolic pathway
series of chemical reactions that start with small molecules and build to create large molecules. Net consumption of energy (ex: photosynthesis)
energy
the capacity to do work
kinetic- energy of motion, electricity
light/radiant energy- photons moving (waves and particles)
thermal- heat
potential energy
stored energy
chemical energy- stored in the bonds of chemical compounds (foods, glucose to produce ATP)
first law of thermodynamics
energy is neither created or destroyed (conserved). It is is utilized by being transferred or transformed
second law of thermodymanics
every energy transfer or transformation, the entropy (increase in disorder) of the universe increase
exergonic
chemical reaction in which there’s a net release of energy, spontaneous, reactants have more free energy and energy is released in the reaction so products have low energy
endergonic
chemical reaction in which there’s a net consumption of energy, non-spontaneous, reactants has low energy and products have high energy
Gibbs free energy
amount of available energy. ΔG=endergonic. -ΔG=exergonic
enthalpy
total amount of energy available or not
energy coupling
the energy released from an exergonic reaction can be used to fuel an endergonic reaction, products can become reactants for another reaction (ex: ATP hydrolysis)
enzymes
protein, catalyst, ends in -ase, lower the activation energy (Ea), stress or strain bonds making them easier to break, environment of the activation site can lower activation energy
catalyst
speeds up the rate of a reaction, not used up during a reaction, substrate specific
activation energy
energy required for a reaction to proceed and reach the transition state
enzyme inhibitors
irreversible- for defense, enzymes will not work again
reversable
reversable inhibitors
competitive- bind directly to active site, block substrates
non-competitive- bind to other locations on enzyme, which causes a conformational (shape) change, moving the active site
negative feedback
when a product deactivates an enzyme, inhibiting the reaction to make more of that same product
