How cells work

Question 1

What is a multimer?

Answer 1

Multiple monomers held together by non-covalent bonds.

Question 2

What is a polymer?

Answer 2

Multiple monomers held together by covalent bonds.

Question 3

What is an oligomer?

Answer 3

An intermediate length polymer, typically more than 10 subunits.

Question 4

What is the difference between ribose and deoxyribose?

Answer 4

Ribose has a OH group on carbon 2 whereas deoxyribose has a H on carbon 2.

Question 5

How is DNA condensed into chromosomes?

Answer 5

by first wrapping around histone proteins to form nucleosomes. Multiple nucleosomes then coil together to form chromatin, which is further looped and folded with the help of other proteins to condense into a chromosome.

Question 6

What do Cathrin coated pits do?

Answer 6

Cathrin coated pits form patches in the membrane that facilitate the formation of vesicles for the transport of macromolecular complexes.

Question 7

Functions of the nucleolus.

Answer 7

• Synthesis of RNA
• Process initial rRNA into smaller fragments
• Pre assembles and exports ribosomes to the cytoplasm

Question 8

What are kinetochores?

Answer 8

kinetochores are the protein complexes that attach to spindle microtubules at the centromeres to facilitate chromosome movement during cell division.

Question 9

What is aneuploidy?

Answer 9

Aneuploidy - When the whole chromosome number differs.

Question 10

What are proteoglycans and where are they found?

Answer 10

They have a protein core with sugar chains attached by covalent bonds.
Found in connective tissues.

Question 11

What is the function of proteoglycans?

Answer 11

Combine with collagen to form cartilage.

Question 12

What feature of proteoglycans helps increase their surface area?

Answer 12

The sugar chains are negatively charged, which are repellent, causing the sugar chains to extend out and maximise the size of the molecule.

Question 13

Name 2 motor proteins.

Answer 13

Kinesin
Dynein

Question 14

What does kinesin do?

Answer 14

Moves vesicles along microtubules towards the positive end of the microtubule.
Moves vesicles away from the nucleus.

Question 15

What do dyneins do?

Answer 15

Move vesicles along microtubules towards the negative end of the microtubule.
Move vesicles towards the nucleus.

Question 16

What are cyclins?

Answer 16

Regulatory proteins who’s levels fluctuate during the cell cycle.

Question 17

What are CDKs?
(cyclin-dependent kinases)

Answer 17

Enzymes activated by cyclins.
Phosphorylate target proteins.
They become active only when bound to a specific cyclin.

Question 18

What is a karyotype?

Answer 18

A complete set of chromosomes.

Question 19

When is karyotyping done?

Answer 19

During metaphase.
Karyotyping is done at metaphase as this is the only stage of the cell cycle when chromosomes are condensed and lined up.

Question 20

The banding pattern on the chromosomes is achieved by staining with a dye. What is the name of that dye?

Answer 20

Giemsa

Question 21

Which part of a chromosome changes in length with each cell division?

Answer 21

Telomere

Question 22

What unwinds the supercoiled DNA?

Answer 22

Topoisomerase

Question 23

what binds a small stretch of RNA to an existing strand of DNA?

Answer 23

Primase

Question 24

What does telomerase do?

Answer 24

Telomerase is an enzyme that helps maintain and extend the telomeres — the protective caps at the ends of chromosomes.

Question 25

What types of disorder would topoisomerase inhibitors be used as part of a treatment plan?

Answer 25

Cancers - as they stop DNA uncoiling which therefore prevents DNA replication.

Question 26

What is an autosome?

Answer 26

A non-sex chromosome.

Question 27

What do microRNA's do?

Answer 27

bind to mRNAs and can either cause mRNA degradation or can inhibit their translation

Question 28

What is cellular differentiation?

Answer 28

Cellular differentiation is defined as the process by which a less specialised cell becomes a more specialised cell.

Question 29

What triggers can cause differentiation?

Answer 29

Change in gene expression. cellular environment. Stem cell division.

Question 30

What is a stem cell?

Answer 30

An undifferentiated cell that is capable of giving rise to an indefinite number of cells of the same type that can give rise to other cell types through differentiation.

Question 31

What can and can't pluripotent cells differentiate into?

Answer 31

Pluripotent cells can give rise to cells from all three germ layers of the embryo: Ectoderm → skin, brain, nerves Mesoderm → muscle, bone, blood Endoderm → lungs, liver, intestines They cannot form the placenta.

Question 32

What stage of the cell cycle does a cell specialise in?

Answer 32

G0

Question 33

Describe the mechanism of autophagy.

Answer 33

formation of a double membrane vesicle called an autophagosome. This encapsulates the cytoplasm, malformed proteins, organelles, or pathogens, and then fuses with the lysosome to form the autolysosome. The contents of the autophaosome are then degraded by acid hydrolysis.

Question 34

Why is autophagy an important process?

Answer 34

Autophagy is very important because it provides a source of energy during cell starvation.

Question 35

Name the 4 types of cell death.

Answer 35

Apoptosis. Necrosis. Anoikis. Autophagy.

Question 36

What is an enzyme?

Answer 36

A macromolecule that catalyses a biochemical reaction.

Question 37

In glycolysis what enzyme catalyses the conversion of glucose to glucose-6-phosphate?

Answer 37

Hexokinase

Question 38

What is allosteric regulation?

Answer 38

the regulation of an enzyme by binding of an effector molecule at a site other than the active site.

Question 39

How do non-competitive inhibitors work?

Answer 39

They alter enzyme activity by binding to the allosteric site of an enzyme.

Question 40

How can acetyl choline esterase inhibitors be used to treat Alzheimer's?

Answer 40

It inhibits the hydrolysis of acetylcholine into acetate and choline so therefore there is more acetylcholine in the synaptic cleft. AChE inhibitors block the acetylcholine esterase enzyme, so acetylcholine stays around longer, improving communication between neurons.

Question 41

what are some differences between necrosis and apoptosis?

Answer 41

Necrosis causes cell swelling, apoptosis causes cell shrinkage. Necrosis causes an inflammatory response, apoptosis doesn't. Apoptosis is regulated but necrosis is not as necrosis is caused by irreversible cell damage.

Question 42

What does an exergonic reaction mean in terms of Gibbs free energy?

Answer 42

Delta G is less than 0. The products have less free energy than the reactants. Reaction can proceed forwards.

Question 43

What does an endergonic reaction mean in terms of Gibbs free energy?

Answer 43

Delta G is greater than 0. The products have more free energy than the reactants. Free energy is required for the reaction to proceed forwards.

Question 44

If a reaction has the correct Gibbs free energy to proceed, is it an exergonic or endergonic reaction?

Answer 44

An exergonic reaction, delta G is less than 0.

Question 45

Describe the structure of ATP.

Answer 45

Ribose sugar. Adenine base. 3 phosphate groups.

Question 46

What are the 2 ways of producing ATP?

Answer 46

Substrate level phosphorylation. Oxidative phosphorylation.

Question 47

Products of the Krebs cycle. (TCA cycle)

Answer 47

2 CO₂ (carbon dioxide) 3 NADH (electron carrier) 1 FADH₂ (another electron carrier) 1 ATP (or 2 for every glucose)

Question 48

What anabolic pathways can glucose-6-phosphate be used in?

Answer 48

Glycogen synthesis. Nucleic acid synthesis. Biosynthesis of triglyceride. Amino acid synthesis. Cholesterol synthesis.

Question 49

Describe the structure of glycogen.

Answer 49

Multi-branched polysaccharide of glucose Glucose molecules linked together by 1,4 glycosidic bonds. At branches linked together by 1,6 glycosidic bonds.

Question 50

What is glycogenesis?

Answer 50

The formation of glycogen from glucose-1-phosphate by glycogen synthase.

Question 51

What is glycogenolysis?

Answer 51

The breakdown of glycogen to glucose-6-phosphate by glycogen phosphorylase.

Question 52

What is gluconeogenesis?

Answer 52

synthesis of glucose from non carbohydrate precursors such as lactate, glycerol and amino acids.

Question 53

What does it mean if the TCA cycle is referred to as being amphibolic?

Answer 53

It serves as both a catabolic and anabolic pathway.