BIO 215 test 1 UPDATED ACTUAL Exam
Questions and CORRECT Answers
Plasma Membrane - CORRECT ANSWER - 4-8 nm thick layer of lipids and protein
Boundary between cell and external environment; defines cell; regulates movement in/out;
mediates communication with external environment ; fluid mosaic (many components;lipids,
phospholipids, cholesterol, proteins); flexible, dynamic structure; not static
Extracellular Matrix - CORRECT ANSWER - Region outside of cell; made of various
proteins/polysaccharides (collagen [fibrous proteins] and cellulose [polysaccharide]); linked to
cell via plasma membrane components (integrins [intermembrane proteins]); Functions:
support/structure (cell walls in plant, bone cells are mostly extracellular matrix) and
adhesion/anchorage to surrounding medium (like to each other to form a tissue or to underlying
medium like a cell is crawling across)
Plant Cell Walls - CORRECT ANSWER - ECM of plant cells; made of cellulose fibers
embedded in other polysaccharides and proteins; functions: mechanical strength,
growth/development, protection; forms tough structure matrix; how cell wall is laid down
outside of plasma membrane regulates which direction cell grows
Prokaryotic Cell Walls -BACTERIA - CORRECT ANSWER - Peptidoglycan: N-
acetylglucosamine and N-acetylmuramic acid [NAG-NAM] (2 types of modified
monosaccharides and dimers) repeat over and over to give long carbohydrate polymer which is
cross linked by little segments of peptides; Beta 1-4
Prokaryotic Cell Wall-ARCHAEA - CORRECT ANSWER - Four known variations:
Sulfated polysaccharides, glycoproteins stabilized by Na+, S-layers-protein chain mail, and
Pseudomurein (N-Acetylglucosamine and N-acetyltalosaminuronic cross linked with peptides
[NAG-NAT]; Beta 1-3
Gram Stain - CORRECT ANSWER - Tool to ID bacteria based on cell wall characteristics;
cells stained with violet dye, rinse with alcohol, stain again with counter-stain (usually red dye)
,Gram Positive - CORRECT ANSWER - Simple cell wall, cell walls have large amount of
peptidoglycan, traps violet dye in cytoplasm, alcohol rinse does not remove violet dye which
masks added red dye, cells appear violet after counter stain is added
Ex: botulism, anthrax, bacterial pneumonia, bacterial meningitis
Gram Negative - CORRECT ANSWER - Complex cell walls with less peptidoglycan, cell
wall located in layer between plasma membrane and an outer membrane, outer membrane has
lipopolysaccharides, violet dye is easily rinsed from the cytoplasm, cells appear pink/red after
counter stain is added
Ex. Plague, whooping cough, STD
Pathogenic gram variable: tuberculosis, leprosy
Prokaryotic Cell-wall Synthesis Inhibitors - CORRECT ANSWER - Certain antibiotics
work by inhibiting cell wall biosynthesis; Ex. Penicillin (isolated from penicillum fungus;
interferes with peptide synthesis and peptidoglycan cross-linking) and Fosfomycin (isolated from
streptomyces; interferes with peptidoglycan biosynthesis; interferes with enzymes involved in
biosynthetic pathway for peptidoglycan)
2. Explain why antibiotics can be used to treat bacterial infections without affecting human cells.
- CORRECT ANSWER - Most bacteria produce a cell wall composed partly of
peptidoglycan which human cells don't make or need. Penicillin, an antibiotic, prevents the final
cross linking step or transpeptidation in assembly of this macromolecule which kills the
bacterium. No harm comes to human host because penicillin does not inhibit any biochemical
processes that goes on within us
Nucleus - CORRECT ANSWER - Large organelle around 5-6 microns in diameter; 10%
total volume. Surrounded by nuclear envelope; double membrane layer. Supported by nuclear
lamina. Punctured at intervals by nuclear pores (regulated openings through nuclear envelope;
control movement of substances in/out of nucleus)
Nuclear Pores - CORRECT ANSWER - Regulated openings through nuclear envelope;
openings controlled by nuclear pore complex which controls movement of substances in/out of
nucleus; have mRNA, ribosomal subunit coming out of nucleus and enzymes, amino acids,
regulatory components of gene expression like steroid hormones, nucleotide starting material all
imported into cell
, Nuclear Lamina - CORRECT ANSWER - Network of intermediate filaments; lie just
beneath inner layer of nuclear envelope; scaffolding that supports nuclear structure; thought to
play role in chromatin organization and organization of material in nucleus; regions in chromatin
that bind to these nuclear lamina elements to help organize it in a specific way
Nucleolus - CORRECT ANSWER - Region within nucleus with clustered regions of
ribosomal RNA genes surrounded by specific RNAs and proteins; site of ribosomal subunit
synthesis; size correlates with activity level; if very active, 25% of size of nucleus
Ribosome - CORRECT ANSWER - Found in all cell types and certain eukaryotic
organelles; it is not an organelle because it is not a membrane bound structure; 25-30 nm;
ribonucleoprotein structures(complex of proteins and RNA); small and large subunit
Prokaryotic ribosomes - CORRECT ANSWER - Large subunit has 2 rRNA molecules
(23S and 5S), 31 proteins that come together to form large subunit (50S) and smaller subunit has
1 ribosomal RNA (16S) and 21 proteins that come together to form small subunit (30S) and
finally form an assembled ribosome that is 70S and 25 nm
Eukaryotic ribosomes - CORRECT ANSWER - Large subunit has 2 rRNA molecules (28S
and 5S), 50 proteins forming a large subunit (60S) and small subunit has rRNA molecule (18S)
and 33 proteins forming a small subunit (40S) and finally form an assembled ribosome that is
80S and 30 nm
Ribosome - CORRECT ANSWER - A site (Aminoactyl tRNA binding site)
P site (Peptidyl-tRNA binding site)
E site (exit site)
mRNA binding site
Prokaryotic Protein-Synthesis Inhibitors - CORRECT ANSWER - Certain antibiotics work
by inhibiting ribosome activity. Ex: tetracyclin (irreversibly binds to 30S subunit of prok.
ribosome and prevents tRNA from entering A site on 70S ribosome) Spectinomycin *interferes
Questions and CORRECT Answers
Plasma Membrane - CORRECT ANSWER - 4-8 nm thick layer of lipids and protein
Boundary between cell and external environment; defines cell; regulates movement in/out;
mediates communication with external environment ; fluid mosaic (many components;lipids,
phospholipids, cholesterol, proteins); flexible, dynamic structure; not static
Extracellular Matrix - CORRECT ANSWER - Region outside of cell; made of various
proteins/polysaccharides (collagen [fibrous proteins] and cellulose [polysaccharide]); linked to
cell via plasma membrane components (integrins [intermembrane proteins]); Functions:
support/structure (cell walls in plant, bone cells are mostly extracellular matrix) and
adhesion/anchorage to surrounding medium (like to each other to form a tissue or to underlying
medium like a cell is crawling across)
Plant Cell Walls - CORRECT ANSWER - ECM of plant cells; made of cellulose fibers
embedded in other polysaccharides and proteins; functions: mechanical strength,
growth/development, protection; forms tough structure matrix; how cell wall is laid down
outside of plasma membrane regulates which direction cell grows
Prokaryotic Cell Walls -BACTERIA - CORRECT ANSWER - Peptidoglycan: N-
acetylglucosamine and N-acetylmuramic acid [NAG-NAM] (2 types of modified
monosaccharides and dimers) repeat over and over to give long carbohydrate polymer which is
cross linked by little segments of peptides; Beta 1-4
Prokaryotic Cell Wall-ARCHAEA - CORRECT ANSWER - Four known variations:
Sulfated polysaccharides, glycoproteins stabilized by Na+, S-layers-protein chain mail, and
Pseudomurein (N-Acetylglucosamine and N-acetyltalosaminuronic cross linked with peptides
[NAG-NAT]; Beta 1-3
Gram Stain - CORRECT ANSWER - Tool to ID bacteria based on cell wall characteristics;
cells stained with violet dye, rinse with alcohol, stain again with counter-stain (usually red dye)
,Gram Positive - CORRECT ANSWER - Simple cell wall, cell walls have large amount of
peptidoglycan, traps violet dye in cytoplasm, alcohol rinse does not remove violet dye which
masks added red dye, cells appear violet after counter stain is added
Ex: botulism, anthrax, bacterial pneumonia, bacterial meningitis
Gram Negative - CORRECT ANSWER - Complex cell walls with less peptidoglycan, cell
wall located in layer between plasma membrane and an outer membrane, outer membrane has
lipopolysaccharides, violet dye is easily rinsed from the cytoplasm, cells appear pink/red after
counter stain is added
Ex. Plague, whooping cough, STD
Pathogenic gram variable: tuberculosis, leprosy
Prokaryotic Cell-wall Synthesis Inhibitors - CORRECT ANSWER - Certain antibiotics
work by inhibiting cell wall biosynthesis; Ex. Penicillin (isolated from penicillum fungus;
interferes with peptide synthesis and peptidoglycan cross-linking) and Fosfomycin (isolated from
streptomyces; interferes with peptidoglycan biosynthesis; interferes with enzymes involved in
biosynthetic pathway for peptidoglycan)
2. Explain why antibiotics can be used to treat bacterial infections without affecting human cells.
- CORRECT ANSWER - Most bacteria produce a cell wall composed partly of
peptidoglycan which human cells don't make or need. Penicillin, an antibiotic, prevents the final
cross linking step or transpeptidation in assembly of this macromolecule which kills the
bacterium. No harm comes to human host because penicillin does not inhibit any biochemical
processes that goes on within us
Nucleus - CORRECT ANSWER - Large organelle around 5-6 microns in diameter; 10%
total volume. Surrounded by nuclear envelope; double membrane layer. Supported by nuclear
lamina. Punctured at intervals by nuclear pores (regulated openings through nuclear envelope;
control movement of substances in/out of nucleus)
Nuclear Pores - CORRECT ANSWER - Regulated openings through nuclear envelope;
openings controlled by nuclear pore complex which controls movement of substances in/out of
nucleus; have mRNA, ribosomal subunit coming out of nucleus and enzymes, amino acids,
regulatory components of gene expression like steroid hormones, nucleotide starting material all
imported into cell
, Nuclear Lamina - CORRECT ANSWER - Network of intermediate filaments; lie just
beneath inner layer of nuclear envelope; scaffolding that supports nuclear structure; thought to
play role in chromatin organization and organization of material in nucleus; regions in chromatin
that bind to these nuclear lamina elements to help organize it in a specific way
Nucleolus - CORRECT ANSWER - Region within nucleus with clustered regions of
ribosomal RNA genes surrounded by specific RNAs and proteins; site of ribosomal subunit
synthesis; size correlates with activity level; if very active, 25% of size of nucleus
Ribosome - CORRECT ANSWER - Found in all cell types and certain eukaryotic
organelles; it is not an organelle because it is not a membrane bound structure; 25-30 nm;
ribonucleoprotein structures(complex of proteins and RNA); small and large subunit
Prokaryotic ribosomes - CORRECT ANSWER - Large subunit has 2 rRNA molecules
(23S and 5S), 31 proteins that come together to form large subunit (50S) and smaller subunit has
1 ribosomal RNA (16S) and 21 proteins that come together to form small subunit (30S) and
finally form an assembled ribosome that is 70S and 25 nm
Eukaryotic ribosomes - CORRECT ANSWER - Large subunit has 2 rRNA molecules (28S
and 5S), 50 proteins forming a large subunit (60S) and small subunit has rRNA molecule (18S)
and 33 proteins forming a small subunit (40S) and finally form an assembled ribosome that is
80S and 30 nm
Ribosome - CORRECT ANSWER - A site (Aminoactyl tRNA binding site)
P site (Peptidyl-tRNA binding site)
E site (exit site)
mRNA binding site
Prokaryotic Protein-Synthesis Inhibitors - CORRECT ANSWER - Certain antibiotics work
by inhibiting ribosome activity. Ex: tetracyclin (irreversibly binds to 30S subunit of prok.
ribosome and prevents tRNA from entering A site on 70S ribosome) Spectinomycin *interferes
