biol 213 unit 2 Flashcards
where does oxidative phosphorylation take place?
inner mitochondrial membrane
where does oxidative phosphorylation take place in aerobic prokaryotes?
plasma membrane
what happens to the activation-energy barrier after each step is catalyzed by an enzyme?
lowers activation-energy barrier
what is kinase general function?
adds phosphate
what is isomerase general function?
rearrangement
what is dehydrogenase’s general function?
catalyzes oxidation by removing H-
what is mutase’s general function?
shifts chemical group
what do catabolic pathways need to accept electrons from oxidation?
NAD+
what is the energy producing step in cellular respiration?
-6
-makes ATP and NADH
-oxidation occurs
what happens in steps 7 and 10?
-substrate-level phosphorylation
-transfer P to ADP
what drives steps 6 and 7?
coupled reactions
what is pyruvate converted into in muscle cells?
lactate
what is pyruvate converted into in yeast cells?
ethanol, CO2
what is the goal of fermentation?
regenerate NAD+ from NADH
what kind of sugar do animal cells store to provide energy at times of fasting?
-glycogen
-stored in cytoplasm of liver and muslce cells
what regulates the balance between glycogen synthesis and breakdown?
intracellular signaling pathways controlled by hormones:
insulin, epinephrine, glucagon
what is starch?
-how plants store glucose
-stored in chloroplasts (along with fats)
how are fats stored in plants and animals?
-lipid droplets
-triacylglycerols
how did chloroplasts and mitochondria evolve?
form bacteria that were engulfed by ancestral cells
how do chloroplasts and mitochondria reproduce?
fission
what are MERRF and myoclonic epilepsy?
-defects in the proteins required for ETC
-experience muscle weakness, heart problems, epilepsy
what can mitochondria do in terms of adaptation?
can adjust their location, shape, and number to suit that particular cell’s needs
why would mitochondria stay fixed in 1 location?
supply ATP directly to a site of unusually high energy consumption
when do mitochondria stay fixed in 1 location?
-in muscle cells- mitochondria are close to contractile apparatus
-in sperm- mitochondria are wrapped tightly around the motile flagellum
mitochondria matrix
contains enzymes for citric acid cycle
inner mitochondrial membrane
-has cristae
-site of oxidative phosphorylation
-helps convert energy from NADH/FADH2 phosphate bond for ATP
outer mitochondrial membrane
-contains porins
-very permeable to small things
outer mitochondrial membrane
contains porins
what are porins?
channel-forming proteins
intermembrane space
contains enzymes for ATP passing out of matrix to phosphorylate
where is pH higher in mitochondria?
pH higher in matrix (less H+)
pH lower in intermembrane space (more H+)
what do redox reactions depend on?
Delta G
e- transfer (depends on relative e- affinities)
what are iron-sulfur centers?
have low e- affinity
have serve as e- acceptors
what are cytochrome proteins?
-transfer proteins
-increase in redox potential (delta E) the further down the ETC they go
what is cytochrome C oxidase>
-has the highest redox potential of all
-oxidized cytochrome c (removes e-)
-has high e- affinity
why is oxygen an electon sink?
has high affinity to e-
but O2- is very dangerous
what dos DNA consist of?
2 long polynucleotide chains held together by H bond between paired bases
what are nucleotides composed of?
nitrogen base and 5-carbon sugar bonded by covalent phosphodiester bonds
what does the backbone of DNA include?
sugar phosphate
what are nucleotides held together by?
phosphodiester bonds between 5’ phophate and 3’ hydroxyl
how many bonds does A T need?
2
how many bonds does G C need?
3
what is gene expression?
the process by which the nucleotide sequence is transcribed into the nucleotide sequence of a protein
for a majority of genes, the final product is____
RNA molecule itself
what are chromosomes?
long, double-stranded DNA molecules packed in
what is chromatin?
DNA that has been compacted by proteins
what are homologous chromosomes?
-2 copies of every chromosome
-1 from mom 1 from dad
what is an example of non-homologous pairs?
sex chromosomes
what is the purpose of staining chromosomes with dyes?
distinguishing between DNA that is rich in A-T nucleotide pairs and G-C pairs
what is a karyotype?
an ordered display of the full set of 46 human chromosomes
what is an example of a change that can be detected on a karyotype?
if a chromosome is lost or switched
what is a gene?
-a segment of DNA that contains the instructions for making a particular protein or RNA molecule
-the functional units of heredity
what is a genome?
the total genetic info carried by a complete set of the chromosomes in the cell/ organism
in many eukaryotes, genes include an excess of _______
interspread, noncoding DNA
what do telomeres do?
-contain repeated nucleotide sequences for the ends of chromosomes to be replicated
-serve as caps that keep chromosome tips from being mistaken by cell as broken DNA
what do centromeres do?
allow duplicated chromosomes to be separated during M phase
what are mitotic chromosomes?
chromosomes in M phase when DNA coils up and condenses severely
what is the nucleolus?
the interphase nucleus
-is large enough to be seen in microscope
what is the purpose of nuncleous?
it is where ribosomal RNAs are created and combine with proteins to form ribosomes
_____ occupy their own distinct territories within the nucleus
interphase chromosomes
what are histone and nonhistone proteins?
proteins that bind to DNA to form eukaryotic chromosomes
what is chromatin?
the complex of both classes of proteins along with nuclear DNA
what does the nucleosome do?
convert the DNA molecules in an interphase nucleus into a chromatin fiber
what is responsible for nucleosome packing?
histones
what does the nucleosome consist of?
-8 histone proteins 2x (H2A H2B H3 H4)
-147 nucleotide pairs that wind around histone octamer
aka nucleosome core and DNA linker
what do nucleases do?
cut the DNA by breaking the phosphodiester bonds between nucleotides
what do chromatin-remodeling complexes do?
use the energy of ATP hydrolysis to change the position of the DNA wrapped around nucleosomes
what do histone-modifying enzymes do?
catalyze the reversible chemical modification of histones
what do chromatin-remoding complexes and histone-modifying enzymes do together?
condense and relax stretches of chromatin - allowing local chromatin structure to change rapidly according to cell’s needs
what is special about interphase chromosomes?
-chromatin isn’t uniformly packed
-regions of the chromosome containing the genes that are actively expressed are generally more extended
what are heterochomatins?
the most highly condensed form of interphase chromatin
what is the euchromatin?
the rest of interphase chromatin
what is responsible for the patchwork coloration of callico cats?
female mammals evolved mechanism for permanently inactivating 1 of 2 X
what does B-globin deactivation cause?
anemia
when a cell divides, what can it pass to its 2 daughter cells?
-histone modifications
-chromatin structure
-gene expression patterns
what is the final product of a new DNA strand?
a complementary in nucleotide sequence to template
DNA polymeraze 3
-monitors base-pairing between each incoming nucleoside triphosphate and template strand
-can correct errors through proofreading
-drives movement of replication fork
-replication machine
-adds deoxyribonucleotides to 3- end of DNA strand
what molecule can correct errors through proofreading?
DNA polymeraze 3
what is proofreading?
enzyme checks whether previously added nucleotide is correctly paired before adding next nucleotide to a growing DNA strand
