Exam 2 Flashcards
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is best know as
Feedback inhibition
A strand of DNA is 30% A. What percentage of it is made up of thymine?
30%
What is a passive process in which molecules move from a region of higher concentration to a region of lower concentration
Diffusion
What types of bonds form between the monomers that make up carbohydrates?
Glycosidic
What type of bonds form between the monomers that make up lipids?
Ester
Proteins are polymers made up of monomers known as
Amino acids
How do enzymes increase the speed of certain biological chemical reactions?
By bringing reactants into physical contact with one another
The kinds of molecules that pass through a cell membrane most easily are
Small and hydrophobic
The type of bond that forms between two nucleotides is known as a
Phosphodiester bonds
What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
Catabolic pathways
What is NAD+ reduced to and when?
To NADH during glycolysis, pyruvate oxidation, and the citric avid cycle
What kind of metabolic poison (toxin) would most directly interfere with glycolysis?
An agent that closely mimics the structure of glucose but is not metabolized
In glycolysis, for each molecule of glucose oxidized to pyruvate ________ molecules of ATP are used and ________ molecules of ATP are produced
2
4
The glucose molecule has a large quantity of energy in its _______
C-H bonds
Why might adding inorganic phosphorus to a reaction mixture where glycolysis is rapidly proceeding help sustain the metabolic pathway?
The metabolic intermediates of glycolysis are phosphorylated
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction _________
Loses electrons and loses potential energy
Why is glycolysis described as having an investment phase and a payoff phase?
It uses stored ATP and then forms a net increase in ATP
In addition to ATP, what are the end products of glycolysis?
NADH and pyruvate
A strand of DNA is 12% C. What percentage of it is made up of T?
38%
Using only single bonds, how many hydrogen atoms would it take to covalently bond to one carbon atom before molecule would become most stable?
4
A cellular membrane that has no cholesterol molecules dispersed throughout phospholipids. If you were to place this organism in an extremely hot environment, what would you expect to see change in regard to cell membrane permeability?
The membrane would become more permeable to glycerol
What kind of reactions link monosaccharides together to form carbohydrates?
Dehydration/condensation
Product A binds to the enzyme that converts X to Y at a position remote from its activation site. The binding decreases the activity of the enzyme. What is the substance A?
An allosteric inhibitor
What two molecules are the major structural components of the cell membrane?
Phospholipids and Proteins
What do prokaryotes include?
Ribosomes
Simple cytoskeleton
Specialized membranes for photosynthesis and the storage of ions or enzymes
What does a prokaryote have instead of a nucleus?
Nucleoid
What is the shape of chromosomes in prokaryotes?
Circular
What are prokaryote’s cell walls made of?
Peptidoglycan
What do prokaryotes contain?
Nucleoid
Plasmids
Circular chromosomes
What do eukaryotes contain?
Nucleus
Complex organelles
What do prokaryotes and eukaryotes both contain?
Ribosomes
DNA
Cell Wall
Plasma Membrane
You have found that an unknown cell type contains DNA, ribosomes, and circular plasmids. Based off this information you know that….
That it is a prokaryote
What are bacterial cells walls made of?
Peptidoglycan
If you are observing a prokaryotic cell under a microscope, which would you expect to find?
A circular chromosome
And ribosomes
What happens if the surface area to volume ratio is too small?
Then the cell can’t get rid of waste or take up nutrients fast enough
Which is the most ideal set of conditions for a cell?
Small volume and large surface area
What does the endomembrane system include?
Cell membrane Endoplasmic reticulum (rough and smooth) Golgi apparatus Lysosomes Peroxisomes Vesicles
What do ribosomes help with?
Protein synthesis
Where do ribosomes start out?
Free-floating in the cytoplasm
Where are the two places ribosomes can go form the cytoplasm?
- stay in the cytoplasm
- dock with the ER if the protein they are making requires it
What is a ribosome dock based on?
Signal sequence
What does the signal sequence allow a ribosome to do?
To bind to an SRP (signal sequence receptor) which binds to a receptor on the ER
Where does a ribosome go after the ER?
(Phagocytosis)
- packaged into transport vesicles
- sent to the Golgi apparatus
- can then be packaged into lysosomes
What are necessary for the endomembrane system to function properly?
Vesicles
What do vesicles do?
They help transport the products from the ER to the Golgi apparatus and so on
How do vesicles move around the cell so easily?
Motor proteins such as kinesins
What are kinesins made of?
2 subunits twisted together
What is the structure of kinesins?
Has a head, a stall, and a tail
What do the tails of kinesins do?
Bind to the vesicle while the heads bind to the microtuble “highways” throughout the cell
What do the heads of kinesins?
“Walk” along the microtubles, moving the vesicle around the cell
What does each “step” of kinesins require?
ATP
A free floating ribosome attaches to a piece of mRNA in the cytoplasm. When protein synthesis begins, no ER signal sequence is present. What is the final destination of this protein?
It will remain within the cell’s cytoplasm
A protein has been packaged into vesicle to be to be secreted. What signal sequences did the mRNA contain that were integrated into the final protein?
ER signal
A cell acquires a mutation to its DNA that causes the Zip Code and Transmembrane sequences to become unreadable in the final protein? Where is the most likely destination for this protein?
It will be secreted to the outside of cell
Which organelle is NOT directly involved in the Endomembrane system?
Mitochondria
What is the order of events of a protein that has an ER and Zip code signal sequence?
- Protein translation beings with a ribosome
- Protein is synthesized in the rough ER
- Protein is transported in vesicle to the Golgi apparatus
- Protein is transported in vesicle to a lysosome
what is substance that resides within the cell’s plasma membrane, but outside of all other cellular organelles and/or compartments?
cytoplasm
What is cytoplasm thickened with?
with ions, salts, and dissolved polar biomolecules
Which cells so not have a nucleus?
prokaryotic
What resides in the nucleoid?
circular DNA chromosome of these cells compacts with the help of some associated proteins for prokaryotes
What is the nucleus?
Organelle that encapsulates the DNA of eukaryotic cells
What is the nuclear envelope?
the double-phospholipid bilayer on the surface of the nucleus
What is the nucleolus?
darkly stained region within the nucleus
Where can molecules pass through the bilayers of the nucleus’s surface?
nuclear pores
What is a combination of proteins and rRNA that does not have membrane?
ribosome
What do ribosomes do?
Takes information from mRNA and assembles amino acids into a protein (translation)
What is rough endoplasmic reticulum?
Organelle attached to the nucleus that is composed of stacks of flattened, circular membranes that are much like the outer cell membrane
Why is rough ER considered rough?
because the surface of these membranes are studded with ribosomes
What is the function of the rough ER?
the synthesis and packaging of proteins for export to outside of the cell
What is smooth endoplasmic reticulum?
Organelle found directly outside of the rough ER that is also composed of stacks of flattened, circular membranes that are much like the outer cell membrane
Why is smooth ER considered smooth?
because the surface of these membranes are NOT studded with ribosomes
What does smooth ER contain?
enzymes for carbohydrate and lipid synthesis and/or degradation
What is the golgi apparatus?
Organelle found directly outside of the ER that is also composed of stacks of flattened, circular membranes much like the outer cell membrane
What is the function of the golgi apparatus?
receiving vesicles, sorting the contents, and re-packaging the contents into a new vesicle to be shipped to a new location
What are the two sides of the golgi?
cis side and the trans side
What does the cis side of the golgi do?
receives vesicles. Because the membranes are similar to the ER, the vesicles fuse with the golgi and dump their contents inside
What is a lysosome?
Organelle that is a product of the golgi
What makes mitochondria and chloroplasts different from other organelles?
Both have 2 membranes
Have their own DNA
“Reproduce” through binary fusion
Very similar to the traits of prokaryotes
What is outside the plasma membrane?
The extracellular matrix
What does the the extracellular matrix help with?
Cell-cell communication, cell-type identity, self-identify (like in the immune system)
What is the extracellular matrix made up of?
Integrins, microfilaments of the cytoskeleton, collagen fibers, proteoglycan molecules, polysaccharide molecules and proteoglycan complex
How do plant cells communicate?
Channels between cells through cell walls: plasmodesmata
How do animal cells communicate?
Gap junctions: span the space between cells to form a channel, directly connecting the cytoplasm of adjacent cells, allows molecules to pass in between
What do tight junctions do?
Holds the membrane of 2 cells together to prevent anything from leaking in between them
What is lipid soluble signaling?
Lipid soluble signals are able to pass through the membrane
They bind with a receptor inside the cytosol of the cell and can bind directly to the targeted gene on DNA
What are lipid insoluble signals?
Unable to pass through the membrane
Bonds with a receptor protein on the outside of the cell
—signal must be transducers into the cytoplasm where it is amplified so it can bind to the DNA
How do plant cells communicate with each other?
Plasmodesmata
If an animal cell wanted to send molecules to an adjacent cell, which type of a cell-cell communication would it use?
Gap junctions