extra Flashcards
Where do the light reactions take place?
Thylakoid membrane of chloroplast
What enzyme catalyzes the fixation of carbon dioxide to an organic molecule?
Rubisco
What are the outputs of the light reaction in photosynthesis?
ATP
NADPH
Oxygen
Photorespiration occurs when…
Rubisco fixes oxygen on the 5-carbon sugar instead of carbon dioxide
How does the modification in C4 plants minimize photorespiration?
Increases carbon dioxide concentration and minimizes oxygen concentration at the point where Rubisco is operating
What is the immediate source of electrons entering the ATP-generating electron transport chain in photosynthesis?
Excited P680
Excited P700
NADPH
Excited P680
What is the immediate output of the Calvin cycle?
Glyceraldehyde-3-phosphate
what produces Co2
CAC, pyruvate oxidation
What are benefits of lactic acid fermentation to an animal cell where aerobic respiration is unavailable?
-Prevents build-up of toxic pyruvate molecules
-Refreshes NADH to NAD+ so glycolysis can continue
What is the function of telomeres?
Buffer the chromosomes against the effects of shortening with each round of replication
Why does anaerobic respiration not generate as much ATP as aerobic respiration?
-The electron acceptor in anaerobic respiration takes electrons before they travel all the way down the electron transport chain and give up all their energy
-Anaerobic respiration does not fully oxidize glucose
Why can translation in prokaryotes start while RNA polymerase is still transcribing a gene?
-Prokaryotic genes do not have introns
-Ribosomes and DNA are not in isolated compartments within prokaryotic cells
Which part of the final, mature RNA molecule was present in the initial RNA transcript, as synthesized by the RNA polymerase?
Exons
The genetic code is unambiguous and redundant. What does this mean?
Each codon codes for one amino acid, but an amino acid may be coded for by several different codons
During translation and protein synthesis, the peptide bond joining the new amino acid to the growing protein is created when…
The protein is detached from the tRNA in the P site and attached to the amino acid on the tRNA in the A site
The basic goal of photosynthesis is use solar energy to energize ______ and store them in sugar molecules.
Electrons
How does a specific mRNA sequence get translated to a specific amino acid sequence?
A given tRNA will only bind to one mRNA codon
A given tRNA will only have type of amino acid attached
What are modifications to the DNA or chromosomes that affect gene expression but do not change the DNA sequence?
Epigenetic modifications
What will a particular activator regulatory transcription factor in eukaryotes bind to?
An enhancer sequence in the regulatory region in front of a few SPECIFIC genes
Why would it be incorrect for a researcher to state that they have found the transcription factor that controls the expression of a particular gene?
Expression of a gene is usually controlled by multiple transcription factors
Which of the two metabolic pathways is found only in prokaryotes?
Anaerobic respiration
Nitrogen fixation
What chemical present in secondary plant cell walls that makes them stronger than primary cell walls?
Lignin
Why is summerwood darker than springwood?
Vessel elements in summerwood are smaller in diameter because there was less water to transport in the summer. The more densely packed cell walls appear darker.
Where is the main site of auxin synthesis, especially in regard to its control of phototropism?
Apical bud/meristem
Auxin stimulates _______, and so as part of phototropism, auxin is present in higher concentrations ________.
Cell elongation; on the shaded side of the stem
What is the purpose of the Casparian strip?
To regulate the concentration of water and minerals being transported around the plant
Loading sucrose into phloem creates a positive pressure in the phloem near the source cells. How is this achieved?
Increased concentration of sucrose in the phloem pulls water osmotically from the xylem into the phloem
What type of tissue is characterized by relatively scattered cells in an extracellular matrix?
Connective tissue
The apoplast in plant tissues may include which of the following?
Cell walls, extracellular spaces, and vessel elements
Food is mixed and pushed along the digestive tract by the contraction and relaxation of alternating bands of muscular tissue within the lining of the small intestine. Which type of muscular tissue is this describing?
Smooth
Sulfur can form two covalent bonds like oxygen, but it is less electronegative than oxygen. Compared to water molecules, how will the H2S molecules behave?
more likely to be a gas at room temp
What feature of dietary fiber is responsible for its role in maintain gastro-intestinal health?
lowers blood cholesterol, Bonds between glucose molecules that cannot be broken by our digestive enzymes
Which of the following statements distinguishes starch and glycogen?
Starch is found in plants, glycogen is found in animals
What monomers make up biological polysaccharides like glycogen and cellulose?
Glucose
Which of the following amino acid substitutions will potentially have the most destabilizing effect on the protein secondary structure?
A polar amino acid changed to a non-polar amino acid
In what part of the cell would a steroid hormone be produced?
Smooth ER
A mutation in the gene that codes for the actin protein would be most likely to affect which type of cell movement?
amoeboid movement
Which of the following statements best describes a key aspect of a G protein signaling pathway?
A G protein is active when bound to GTP
