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BIOS
BIOS 242 MIDTERM EXAM QUESTIONS WITH
CORRECT VERIFIED ANSWERS LATEST UPDATE
(2024/2025) GUARANTEED PASS
External structures of Archaea - ANS ✓Glycocalyces-like bacteria, composed of
polysaccharides, polypeptides, or both. In archaea glycocalyces function in
forming biofilms by adhering cells to each other, to other types of cells and to
inanimate surfaces. In bacteria biofilms are connected to disease but in archaea
they are not.
Flagella- same as bacteria, basal body, hook and filament.
Different from bacteria in that they are thinner, have proteins with distinct
amino acid sequences compared to the proteins of bacterial flagella, and
are powered by energy stored in atp.
Fimbriae and Hami- most archea have fimbriae that anchor the cells to one
another and to environmental surfaces. Some archaea have unique fibriae
like structures called hami that also function to attach archaea to biological
and inanimate surfaces.
Archaeal cell walls and cell membranes - ANS ✓most archaea have cell walls
but dont have peptidoglycan like bacterial cell walls. Also are gram positive or
negative based on cell wall components. Cell wall functions like that of bacteria.
Cytoplasm of archaea - ANS ✓like bacteria, do not have membranous
organelles in cytoplasm, and have 70S ribosomes but the ribosomes are
composed of proteins more similar to those of eukaryotic ribosomes, and the
enzymes archaea use to make rna are diff from those used by bacteria. Also the
genetic code of archaea is more like that of eukaryotes.
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Glycocalyces in eukaryotes - ANS ✓absent in cells w cell walls but present in
cells without cell walls like animal and protozoan cells. Glycocalyx anchored to
cell membrane and functions in strengthening cell surface, provide protection
against dehydration, and cell to cell recognition and communication
Eukaryotic cell wall - ANS ✓if it has a cell wall its composed of polysaccharides
Fungi-chitin cell wall
Algae- agar, carrageenan, algin cell wall
Plants-cellulose cell wall
Eukaryotic cell membrane - ANS ✓all eukaryotes have cell membrane.
Phospholipids and proteins like bacterial cells. Unlike bacteria, contains steroids
that strengthen membrane when temporises and falls and maintain fluidity.
Contain regions of lipids and proteins called membrane rafts.
Endocytosis - ANS ✓some eukaryotic cells transport substances into cytoplasm
w endocytosis which is active process where pseudopodia (movable extensions
of the cytoplasm and cell membrane) surround a substance and move it into a
cell. If its a solid brought in its called phagocytosis. If its a liquid brought in its
pinocytosis.
Eukaryotic flagella - ANS ✓Differ structurally and functionally from prokaryotic
flagella
Within the cytoplasmic membrane
Shaft composed of tubulin arranged to form microtubules
Filaments anchored to cell by basal body, no hook
May be single or multiple, generally found at one pole of cell
Do not rotate but undulate rhythmically to push or pull cell through the
medium
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Eukaryotic cilia - ANS ✓Shorter and more numerous than flagella
Coordinated beating propels cells through their environment
Also used to move substances past the surface of the cell
Nonmembranous organelles in eukaryotes - ANS ✓Ribosomes-Larger than
prokaryotic ribosomes (80S versus 70S) Composed of 60S and 40S subunits
Cytoskeleton- Extensive network of fibers and tubules
Anchors organelles, Produces basic shape of the cell, Made up of tubulin
microtubules, actin microfilaments, and intermediate filaments
Centrioles-play a role in mitosis, cytokinesis, and formation of flagella and
cilia
Centrosome- region of cytoplasm where centrioles are found
Eukaryotic nucleus - ANS ✓largest organelle in cell
Contains most of the cell's DNA
Semi-liquid portion called nucleoplasm Contains chromatin and one or
more nucleoli which is where rna is synthesized
Surrounded by nuclear envelope which Contains nuclear pores
Endoplasmic Reticulum - ANS ✓Netlike arrangement of flattened, hollow
tubules continuous with nuclear envelope
Functions as transport system
Smooth endoplasmic reticulum (SER)- lipid synthesis and transport
Rough endoplasmic reticulum (RER)- ribosomes stuck to surface and
produce proteins that are transported throughout the cell.
Golgi body - ANS ✓Not in all eukaryotic cells
Flattened hollow sacs surrounded by phospholipid bilayer.
Receives, processes, and packages large molecules for export from cell in
secretory vesicles that fuse with cytoplasmic membrane
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Lysosomes peroxisomes vacuoles and vesicles - ANS ✓Store and transfer
chemicals within cells
May store nutrients in cell
Lysosomes contain catabolic enzymes, self destruction of cells.
Peroxisomes contain enzymes such as oxidase and catalase that degrade
poisonous wastes like free radicals and hydrogen peroxide.
Mitochondria - ANS ✓Have two membranes composed of phospholipid bilayer
Produce most of cell's ATP, powerhouses of cell
Interior matrix contains 70S ribosomes and circular molecule of DNA
Innermost membrane= folded cristae, increases surface area for atp
production
Chloroplasts - ANS ✓light harvesting structures in photosynthetic eukaryotes.
Pigments gather light energy to produce atp from sugar and co2.
Thylakoids- numerous membranous sacs for extensive surface area for
biochemical reactions.
Like mitochondria, chloroplasts have 2 phospholipid bilayer membranes,
circular DNA and 70s ribosomes.
Endosymbiotic theory - ANS ✓explains why mitochondria and chloroplasts
have 70s ribosomes, circular DNA, and 2 membranes.
Theory says that Eukaryotes formed from union of small aerobic
prokaryotes with larger anaerobic prokaryotes
Smaller prokaryotes became internal parasites
Parasites lost ability to exist independently
Larger cell became dependent on parasites for aerobic ATP production
Aerobic prokaryotes evolved into mitochondria
Similar scenario for origin of chloroplasts
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