bio112

Question 1

prokaryotes can be divided into which 2 domains

Answer 1

bacteria and archaea

Question 2

biological applications for extremophiles

Answer 2

pcr
biofuels
biomining
carotenoid production
detergents

Question 3

components of prokaryotic cells

Answer 3

nucleiod , ribosomes , plasma membrane , cell wall , capsule

Question 4

magnification

Answer 4

ratio of objects image size to real size

Question 5

resolution

Answer 5

measure of minimum distance of two distinguishable points

Question 6

contrast

Answer 6

visible differences in brightness or colour between parts of the sample

Question 7

Deconvolution microscopy

Answer 7

Algorithms remove out of focus light and this sharpens the image and improves resolution

Question 8

Super resolution

Answer 8

gathers light from individual fluorescent molecules and records their position. Combining information from these individual molecules breaks the resolution limit

Question 9

scanning electron microscope

Answer 9

electrons reflected on surface and collected by electron detector and converted into electron signal

Question 10

uses for cell fractionation

Answer 10

Protein Enrichment
•Enrich target proteins and improve detection of low abundance protein
Protein Characterization
•Identify the subcellular localization of a protein
Protein Translocation
Monitor translocation of cell signalling molecules from the cytoplasm to the nucleus

Question 11

lipid molecules form what in aqueous envieonments

Answer 11

micelles or bilayers

Question 12

smooth endoplasmic reticulum

Answer 12

phospholipid , fat and steriod manufacturer
carbohydrate metabolism
breaks down stored glycogen to release glucose
detoxifies lipid soluble drugs such as barbiturates

Question 13

sarcoplsdmic reticulum

Answer 13

found in muscle cells
network of tubular sacs
transmits electrical signals
sequesters calcium ions from systole
level of intereceullar calcium regales muscle contractions. in cells

Question 14

myofibrils

Answer 14

composed of repetitive arrangements of filaments called a sarcomere ( a region where myosin and acton filaments overlap )

Question 15

H line

Answer 15

only myosin
shortens during contraction

Question 16

A line

Answer 16

region containing length of dingle myosin filament

Question 17

RER

Answer 17

protein synthesissecreted glyocsylated lysosomal enzymes membrane bound proteins

Question 18

protein synthesis in the RER

Answer 18

ribosome synthesiseing Poetin w specific signal peptide attaches to RER
N terminus of proteins contains a signal peptide
signal recognition particle attaches to signal peptide and stops tranlastio in cystol
SRP docks to its receptor om membrane and translation starts again
hydrophobic signal peptide passes thru membrane and loops back thru membrane and is cleaved off . erst of peptide passes thru membrane and into ER lumen .

Question 19

glyoclisation inn the RER

Answer 19

addition of sugars
oligosaccharide added in RER . composed of N - acetylglucosamine , mannose and glucose resides containing 124 sugar residues and transfers to the proteins in RER

Question 20

endosymbiotic theory of mitochondrial origin

Answer 20

•Own circular genome
•Double membrane
•Similar in size to prokaryotic cell
•Divide by binary fission

Question 21

Prokaryotic Cell

Answer 21

Prokaryotic cells are unicellular organisms lacking membrane-bound organelles and a true nucleus. Their DNA is located in a nucleoid region.

Question 22

Domains of Prokaryotes

Answer 22

Two main domains: Bacteria and Archaea. Bacteria: medically/economically significant. Archaea: often extremophiles, thriving in harsh environments.

Question 23

Key Structural Features of Prokaryotic Cells

Answer 23

Plasma membrane, cytoplasm, nucleoid, ribosomes. Optional structures: cell wall, flagella, pili, capsule. DNA is circular; additional genes may be on plasmids.

Question 24

Bacterial Cell Shapes

Answer 24

Cocci - spherical, Bacilli - rod-shaped, Spirochetes - spiral-shaped.

Question 25

Prokaryotic Cell Wall Types

Answer 25

Gram-positive: Thick peptidoglycan wall, teichoic acids present. Stains purple, more antibiotic susceptible. Gram-negative: Thin peptidoglycan layer, outer membrane with lipopolysaccharides. Stains pink, more resistant to antibiotics.

Question 26

Prokaryotic Modes of Nutrition

Answer 26

Photoautotrophs: Light + CO₂, Chemoautotrophs: Inorganic molecules + CO₂, Photoheterotrophs: Light + organic compounds, Chemoheterotrophs: Organic compounds for energy and carbon.

Question 27

Archaea and Extremophiles

Answer 27

Archaea thrive in extreme conditions: high salt, temperature, or acidity. Example: Thermus aquaticus used in PCR due to heat-stable enzymes. Potential model for extraterrestrial life.

Question 28

Viruses - Basic Structure

Answer 28

Not cells; not alive. Consist of nucleic acid (DNA/RNA) enclosed in a protein capsid made of capsomers. Some have a lipid envelope (e.g., influenza, SARS-CoV-2).

Question 29

Types of Viruses

Answer 29

Filamentous: e.g., Tobacco mosaic virus. Spheroid: e.g., Adenovirus. Enveloped: e.g., Coronaviruses. Tailed Spheroid: e.g., Lambda phage.

Question 30

Bacterial Use in Biotechnology

Answer 30

Medical: Insulin production, drug screening. Agriculture: Genetically modified crops (e.g., purple tomatoes). Environment: Bioremediation. Industry: Lactic acid bacteria in food and wine production.

Question 31

Light microscope sample preparation

Answer 31

Whole mounts: small relatively transparent specimens mounted directly onto slides Tissue sections: most tissues need to be sectioned before they can be examined Fixation: This involves using chemical fixatives to prevent cell autolysis and to preserve the structure of the tissue. Dehydration and clearing: This removes the water from the tissue in preparation for wax impregnation Embedding: The specimen is infiltrated with molten wax, after which it is transferred to a mould Sectioning: Thin sections approximately 5 microns thick are cut on a microtome, and collected onto a glass slides Staining: The wax is removed and the tissue stained with a coloured dye such as Eosin (cytoplasm) or haematoxylin (nuclei)

Question 32

Advanced light microscopy

Answer 32

•Permits observation of transparent living cells•Light phase shifts induced by specimen are used to generate contrast •Phase contrast (refracted and unrefracted light)•Differential interference contrast (two light beams)

Question 33

Deconvolution microscopy

Answer 33

•Algorithms remove out of focus light and this sharpens the image and improves resolution.

Question 34

Super resolution

Answer 34

gathers light from individual fluorescent molecules and records their position. Combining information from these individual molecules breaks the resolution limit.

Question 35

Membrane Proteins

Answer 35

Transmembrane proteins are amphipathic they have hydrophobic regions and hydrophilic regions Peripheral membrane proteins are only associated with the membrane by non-covalent linkages and are easily dislodged

Question 36

Freeze-fracture electron microscopy

Answer 36

1)Fixation and preservation with glycerol2)Rapid Freezing – liquid nitrogen3)Fracturing – under pressure using a liquid nitrogen cooled microtome4)Replication5)Replica cleaning

Question 37

Membrane Proteins have Many Functions

Answer 37

Transport protein. E.g. the sodium/potassium ATPase pump which pumps 3 sodium ions out of the cell and 2 potassium ions into the cell Receptor sites: the exterior region of a transmembrane protein may act as a receptor for a chemical messenger such as a hormone or growth factor. Structural roles: Membrane proteins called Integrins allow the cell to attach to the extracellular matrix Cell junctions: Tight junctions are present between some cell types. They act to separate the apical and basal membranes which have different functions.

Question 38

The Endomembrane System

Answer 38

A network of membrane-bound structures unique to eukaryotic cells, including the nuclear envelope, smooth and rough ER, Golgi apparatus, lysosomes, and vesicles.

Question 39

Smooth Endoplasmic Reticulum (SER)

Answer 39

Interconnected tubules lacking ribosomes. Functions: Lipid and steroid synthesis, carbohydrate metabolism, detoxification, and calcium storage (in hepatocytes and muscle cells).

Question 40

Sarcoplasmic Reticulum (SR)

Answer 40

A specialized SER found in muscle cells. Stores and releases calcium ions, which trigger muscle contraction by binding to troponin, causing tropomyosin to shift and expose actin-binding sites.

Question 41

Rough Endoplasmic Reticulum (RER)

Answer 41

Studded with ribosomes. Functions: Synthesis of secreted proteins, membrane-bound proteins, lysosomal enzymes, and glycoproteins.

Question 42

Signal Mechanism for ER Targeting

Answer 42

Signal peptide at N-terminus of proteins directs them to RER. Recognized by signal recognition particle (SRP), which pauses translation. SRP docks to ER, translation resumes, peptide enters lumen, and signal is cleaved by signal peptidase.

Question 43

Ribosomes and Polyribosomes

Answer 43

Ribosomes synthesize proteins by translating mRNA. Polyribosomes: Multiple ribosomes attached to a single mRNA strand, increasing translation efficiency.

Question 44

Glycosylation in the RER

Answer 44

Oligosaccharides (14 residues long) are added to proteins. Composed of N-acetylglucosamine, mannose, and glucose. Essential for proper protein folding and function.

Question 45

Golgi Apparatus

Answer 45

Receives proteins from RER via vesicles. Modifies (mainly glycosylates), sorts, and ships proteins to final destinations: secretion, plasma membrane, or organelles like lysosomes.

Question 46

Mannose-6-Phosphate (M6P) Pathway

Answer 46

In cis-Golgi, lysosomal enzymes are tagged with M6P. M6P receptors in the trans-Golgi direct them to lysosomes.

Question 47

Glycosylation in the Golgi

Answer 47

Adds complex sugar chains to proteins. Essential for forming mucins, large glycoproteins in mucus. Defective glycosylation linked to cystic fibrosis.

Question 48

Lysosomes

Answer 48

Membrane-bound organelles containing ~60 hydrolytic enzymes. Functions: Autophagy: recycling organelles, Phagocytosis: engulfing pathogens, Apoptosis: programmed cell death.

Question 49

Lysosomal Storage Diseases

Answer 49

Caused by defective enzymes leading to accumulation of undegraded materials. Example: Tay-Sachs disease - deficiency in hexosaminidase A, causes ganglioside build-up in neurons.

Question 50

Exocytosis

Answer 50

Vesicles fuse with the plasma membrane to export materials like hormones, mucus, and proteins. Important in secretion and cell communication.

Question 51

Types of Endocytosis

Answer 51

Phagocytosis: Engulfing large particles or pathogens. Pinocytosis: Non-specific uptake of extracellular fluid. Receptor-mediated endocytosis: Specific uptake using clathrin-coated vesicles (e.g., transferrin or SARS-CoV-2).

Question 52

Clathrin and Endocytosis

Answer 52

In receptor-mediated endocytosis, clathrin polymerizes around forming vesicles, creating a cage-like structure that enables selective internalization of macromolecules.