Molecular Cell Biology Exam
questions and answers graded A+
The cell theory - ANS✅✅-All living organisms are made up of one or more cells.
-the cell is the fundamental unit of structure and function in all living organisms.
-all cells are essentially the same in chemical composition.
The central dogma - ANS✅✅The flow of genetic information in all living cells.
-DNA>RNA>PROTEIN
-replication>transcription>translation
Polytene chromosomes from Drosophila - ANS✅✅The giant salivary gland cells of the Drosophila
larva go through multiple rounds of DNA replication with NO cell division, resulting in polytene
chromosomes.
The Miller-Urey experiments - ANS✅✅1950's
-It recreated the conditions thought to exist in the primitive earth.
-seven simple molecules (all gasses): water, nitrogen, ammonia, carbon monoxide, carbon dioxide,
methane and hydrogen. NO OXYGEN.
-Heat: evaporates water.
-Radiation: (electrodes discharged sparks into main chamber, simulating lighting): provides energy to
arrange the simple gases into more complex structures.
-a cooling system captures molecules into liquid form for examination.
What were the results of the Miller-Urey experiment? - ANS✅✅With each round of heating,
radiation and cooling, more complex organic molecules were formed:
1. aldehydes
2. simple acids
3. more complex acids (including amino acids), many of them found in living systems today.
-these experiments suggested that organic molecules could form under the conditions that existed
in the primitive earth.
,The formation of self- replicating macromolecules - ANS✅✅The advent of self-replicating
macromolecules was the next step in the origin of life.
-necessary for REPRODUCTION and EVOLUTION.
-present day: Nucleic acids.
which macromolecule is double stranded and which is single stranded? - ANS✅✅Double: DNA
Single: RNA
The first genetic system might have been ___ based. - ANS✅✅RNA
Some RNA molecules (ribozymes) have what kind of activity? - ANS✅✅enzymatic activity.
The ribozyme and the substrate may be two separate RNA molecules, or two domains of the same
RNA molecule observed in: - ANS✅✅1. genome replication in some RNA viruses.
2. intron splicing
What are the two evidence of the RNA world? - ANS✅✅1. some RNA molecules (ribozymes) have
enzymatic activity.
2. RNA can catalyze the polymerization of nucleotides, including the synthesis of complimentary
RNA, using itself as template. (this is NOT observed in DNA)
In the hypothetical RNA world, RNA molecules can catalyze ______? - ANS✅✅can catalyze the
replication of themselves and of other nucleic acids.
Can RNA direct protein synthesis? - ANS✅✅yes. evolution of new enzymes that create DNA and
make RNA copies from it.
What was the first cell? - ANS✅✅A self-replicating RNA and other life-promoting molecules inside
a phospholipid membrane. RNA was replaced in living cells by the more stable DNA, but retained its
properties.
Phospholipid molecule - ANS✅✅-the head group: hydroPHILIC.
-the tail group: hydroPHOBIC.
, Why are cells so small? - ANS✅✅1. Greater surface area to volume ratio.
2. as the radius increases, the increase in volume is faster than the increase in cell surface area.
3. high surface area to volume ratio means more membrane area per unit of volume: this is
important for the interactions between the cells and its environment.
4. smaller cells can interact with their surroundings more efficiently.
5. smaller cells (and animals) are also more prone to lose energy as heat to their surroundings.
6. smaller animals need to eat more than larger animals (as a percent of their own mass).
Prokaryotes - ANS✅✅(Bacteria and Archaea) lack a nuclear envelope, organelles and a
cytoskeleton.
Eukaryotes - ANS✅✅have a nuclear envelope (the defining feature), organelles, and a
cytoskeleton.
Escherichia coli - ANS✅✅-no nucleus
-no organelles
-single chromosome (in the nucleic area) + plasmids
-cell wall
-capsule
-PROKARYOTIC CELL
what cells are the most diverse? - ANS✅✅Prokaryotes
What type of bacteria have spherical cells? - ANS✅✅Streptococcus
What type of bacteria have rod-shaped cells? - ANS✅✅E. coli, salmonella
What type of bacteria have spiral cells? - ANS✅✅Treponema pallidum
Photosynthetic bacteria - ANS✅✅obtain energy from sunlight.
-these cells have an internal system of membranes where photosynthesis occurs ( in photosynthetic
eukaryotes such as plants, this system of membranes is the organelle chloroplast.)
questions and answers graded A+
The cell theory - ANS✅✅-All living organisms are made up of one or more cells.
-the cell is the fundamental unit of structure and function in all living organisms.
-all cells are essentially the same in chemical composition.
The central dogma - ANS✅✅The flow of genetic information in all living cells.
-DNA>RNA>PROTEIN
-replication>transcription>translation
Polytene chromosomes from Drosophila - ANS✅✅The giant salivary gland cells of the Drosophila
larva go through multiple rounds of DNA replication with NO cell division, resulting in polytene
chromosomes.
The Miller-Urey experiments - ANS✅✅1950's
-It recreated the conditions thought to exist in the primitive earth.
-seven simple molecules (all gasses): water, nitrogen, ammonia, carbon monoxide, carbon dioxide,
methane and hydrogen. NO OXYGEN.
-Heat: evaporates water.
-Radiation: (electrodes discharged sparks into main chamber, simulating lighting): provides energy to
arrange the simple gases into more complex structures.
-a cooling system captures molecules into liquid form for examination.
What were the results of the Miller-Urey experiment? - ANS✅✅With each round of heating,
radiation and cooling, more complex organic molecules were formed:
1. aldehydes
2. simple acids
3. more complex acids (including amino acids), many of them found in living systems today.
-these experiments suggested that organic molecules could form under the conditions that existed
in the primitive earth.
,The formation of self- replicating macromolecules - ANS✅✅The advent of self-replicating
macromolecules was the next step in the origin of life.
-necessary for REPRODUCTION and EVOLUTION.
-present day: Nucleic acids.
which macromolecule is double stranded and which is single stranded? - ANS✅✅Double: DNA
Single: RNA
The first genetic system might have been ___ based. - ANS✅✅RNA
Some RNA molecules (ribozymes) have what kind of activity? - ANS✅✅enzymatic activity.
The ribozyme and the substrate may be two separate RNA molecules, or two domains of the same
RNA molecule observed in: - ANS✅✅1. genome replication in some RNA viruses.
2. intron splicing
What are the two evidence of the RNA world? - ANS✅✅1. some RNA molecules (ribozymes) have
enzymatic activity.
2. RNA can catalyze the polymerization of nucleotides, including the synthesis of complimentary
RNA, using itself as template. (this is NOT observed in DNA)
In the hypothetical RNA world, RNA molecules can catalyze ______? - ANS✅✅can catalyze the
replication of themselves and of other nucleic acids.
Can RNA direct protein synthesis? - ANS✅✅yes. evolution of new enzymes that create DNA and
make RNA copies from it.
What was the first cell? - ANS✅✅A self-replicating RNA and other life-promoting molecules inside
a phospholipid membrane. RNA was replaced in living cells by the more stable DNA, but retained its
properties.
Phospholipid molecule - ANS✅✅-the head group: hydroPHILIC.
-the tail group: hydroPHOBIC.
, Why are cells so small? - ANS✅✅1. Greater surface area to volume ratio.
2. as the radius increases, the increase in volume is faster than the increase in cell surface area.
3. high surface area to volume ratio means more membrane area per unit of volume: this is
important for the interactions between the cells and its environment.
4. smaller cells can interact with their surroundings more efficiently.
5. smaller cells (and animals) are also more prone to lose energy as heat to their surroundings.
6. smaller animals need to eat more than larger animals (as a percent of their own mass).
Prokaryotes - ANS✅✅(Bacteria and Archaea) lack a nuclear envelope, organelles and a
cytoskeleton.
Eukaryotes - ANS✅✅have a nuclear envelope (the defining feature), organelles, and a
cytoskeleton.
Escherichia coli - ANS✅✅-no nucleus
-no organelles
-single chromosome (in the nucleic area) + plasmids
-cell wall
-capsule
-PROKARYOTIC CELL
what cells are the most diverse? - ANS✅✅Prokaryotes
What type of bacteria have spherical cells? - ANS✅✅Streptococcus
What type of bacteria have rod-shaped cells? - ANS✅✅E. coli, salmonella
What type of bacteria have spiral cells? - ANS✅✅Treponema pallidum
Photosynthetic bacteria - ANS✅✅obtain energy from sunlight.
-these cells have an internal system of membranes where photosynthesis occurs ( in photosynthetic
eukaryotes such as plants, this system of membranes is the organelle chloroplast.)
