L1,2 and 3: Cell structure and function, and nucleotides

Describe three differences between prokaryotic and eukaryotic cells

• Prokaryotic has 70s ribosomes, eukaryotic has 80s

• Prokaryotic cells do not have a true nucleus, eukaryotic cells do

• Prokaryotic cells have no membrane- bound organelles, eukaryotic do- adv for prokaryotic as replication is faster and requires less energy

Describe the head of a triglyceride

Phosphate and glycerol

Hydrophilic

Polar

Describe the tail of a triglyceride

Fatty acid

Non polar

Hydrophobic (allows passive permeability of lipid soluble molecules)

What are the purposes of phospholipids in a cell

• Signalling

• Attachment- virus needs specific receptors to attach and invade

• Barrier

Describe a hypertonic, hypotonic and isotonic solution

Hypertonic- More sugar outside, water diffuses out of cell, shrinkage

Isotonic- no overall net movement

Hypotonic- More sugar inside the cell, water moves in, cell swelling and bursting

What is the function of the smooth endoplasmic reticulum

Lipid and carbohydrate synthesis

Storing intracellular Ca2+

Detoxification (e.g. in hepatocytes (liver cells))

Describe the structure of a eukaryotic ribosome

80s- 60s and 40s subunits

Describe the makeup of a eukaryotic ribosome

2/3 made up of ribosomal RNA

1/3 made up of ribosomal protein

Describe the structure of a prokaryotic ribosome

70s- 50s and 30s subunits

How does a drug bind to a ribosome?

Drug binds to either the small or large subunit

How is the surface area of mitochondria increased?

Cristae- folding

What is the function of the matrix in mitochondria?

Holding enzymes

Describe the organisation of the nucleus

• Nucleolus (rRNA synthesis and ribosome assembly)

• Chromatin (condense and package chromosomal DNA)

• Nuclear envelope with nuclear pores

• Rough endoplasmic reticulum- continuous with outer membrane of nucleus

What are the actual names for DNA and RNA

Deoxyribonucleic acid and ribonucleic acid

What is the difference in structure of DNA and RNA

RNA has an additional OH group attached to the ribose sugar

Describe the difference between a purine and pyrimidine, and which bases are which

Pyrimidine- Single ring: thymine, cytosine, uracil

Purine- Double ring: adenine, guanine

In ATP, what is the name of the bonds between the phosphate groups?

Phosphoanhydride bonds

How much energy does the hydrolysis of an ester bond yield?

14KJ/mol

How much energy does the hydrolysis of a phosphoanhydride bond yield?

30KJ/mol

How much ATP des the average person have?

100g

What is the function of glycolysis, and what is produced?

The breakdown of glucose (6 carbon) to pyruvate (2× 3 carbon), with a net gain of 2 ATP and 2 NADH

After glycolysis, what happens if there is no oxygen present?

Pyruvate is converted to lactate using lactate dehydrogenase. Lactate is important as it regenerates NAD from NADH so glycolysis can continue

After glycolysis, what happens if oxygen is present?

The link reaction converts pyruvate to acetyl coA

Describe oxidative phosphorylation

• Inner mitochondrial membrane

• Requires oxygen

• Electron transport chain- NADH and FADH2 donate electrons to chain.

• Complex 1, complex 2….. complex 5 (ATP synthase)

What is the purpose of the pentose phosphate pathway?

NADP+ —> NADPH.

NADPH is regenerated by the PPP

Does NADP+ play a role in ATP regeneration?

No

What is the function of NADPH?

Reductive biosynthesis- synthesis of fatty acids and cholesterol

Describe the Krebs cycle

Oxaloacewtate combines with acetyl coA to form citrate. Oxaloacetate is reproduced, and NADH and FADH2 are produced, which carry electrons for electron transport chain in oxidative phosphorylation

Explain where the production of ATP comes from in respiration

2x NADH glycolysis, 2x NADH link reaction, 2x NADH Krebs cycle. 3 ATP per NADH. 3×10=30

2x FADH krebs cycle. 2 ATP per FADH. 2×2=4

Glycolysis and Krebs cycle have a net gain of 2 ATP each

30+4+2+2= 38

What is cyclic AMP and when is it produced?

Second messenger, produced in response to hormones (first messenger)

How is cAMP formed?

Formed from ATP catalysed by adenylate cyclase

Explain the importance of signalling in the heart

• Primary messenger binds to receptor

• Conformational change occurs (changes shape of protein)

• Activates adenylate cyclase to convert ATP to cAMP, which amplifies the original hormone signal