Cellular functions: protein synthesis, respiration and communication

Key functions of proteins (4)

-binding

-catalysis

-switching

-structure and motion

Protein synthesis

DNA of each cell holds complete set of instructions for cellular protein synthesis

DNA

Double stranded chain on nucleic acid, twisted to form double helix (1 coding and 1 template strand)

What does DNA chain consists of

Polymer of nucleotides

What do nucleotides consists of

-sugar

-phosphate

-nitrogenous base

What is the blueprint of protein synthesis

Base sequences

Where is DNA located

Nucleus

Where is amino acids located

Ribosome

What is transcription

DNA passes on instructions to cytoplasm by synthesising mRNA with copy of code for protein required

Where does transcription take place

Nucleus

What is translation

MRNA directs the building of the protein

What does tRNA do

Delivers a particular amino acid to be added to protein chain

List 3 steps in translation

1. Initiation

2. Elongation

3. Termination

What is initiation

Major groups come together

What is elongation

Additional amino acids added in correct order

What is termination

End of protein synthesis signalled

What are exons

Coding regions

What are introns

Non coding regions

What happens during transcription

Entire generation is copied into a pre mRNA, includes exon and introns

What happens at RNA splicing

Introns are removed and exons are joined to form contiguous coding sequence

Genes switched on is what?

Expressed

Genes switched off is what?

Repressed (SRY gene)

What are housekeeping genes

Genes that code for proteins universally used in all cells

Gene regulation occurs by (2)

-epigenetics

-cellular environment

Where are proteins made

Ribosome

How proteins are formed

Enter RER, then Golgi body

What is added to proteins to give functionality

Carbohydrates or lipids

What is a mutation

Permanent change in DNA

Give an example of a mutation that relates to eye

Retinal degeneration

How is accidental damage to DNA or errors in transcription/translation corrected

DNA repair mechniasms

What is retinitis pigmentosa

Mutated form of normal genes prevent production of protein essential for function of photoreceptor

How is ATP made

ADP + P

What is ADP + P converted to

ATP

What is cellular respiration

Breakdown of food (glucose) to release energy

Where does cellular respiration occur

Mitochondria

How many sets of controlled reactions that allow energy transfer are there

4

Name the 4 sets of controlled reactions to allow energy transfer

1. Glycolysis

2. Formation of acetyl co-enzyme A

3. Krebbs cycle

4. Electron transport chain

Describe process of glycolysis

Glucose —-> Pyruvic acid

How much ATP is produced from glycolysis

2

Describe process of formation of acetyl co enzyme A

Pyruvic acid —-> CoA

Describe krebbs cycle

Co A —-> Co^2

How much ATP is produced from ETC

32

Does aerobic respiration require oxygen or no?

Yes

Does anaerobic respiration require oxygen

No

Example off aerobic respiration

Krebs cycle & ETC

Examples of anaerobic respiration

Glycolysis

What happens in aerobic respiration when there is no oxygen

Pyruvic acid is converted to lactic acid, allowing some ATP to be produced

Where does the highest rate of aerobic glucose consumption occur in the body

Retina

Name 3 results of excess glucose in body

-diabetes

-high circulating glucose levels

Cardiovascular, skin, nerve damage

Describe diabetes

Glucose not metabolised properly due to insulin production being disturbed

Gap junctions

Clusters of intracelluar channels that allow direct diffusion of ions and small molecules between adjacent cells

Example of extracellular signalling junctions

Pannexin channels

What do gap junctions allow for

Exchange of water, inorganic ions and small biomolecules

What do gap junctions integrate

Integrate the electrical and metabolic activities of cells forming interacting populations

What do gap junctions permit

Co ordinated signalling in tissues

Role of gap junctions in heart

Synchronisation of heartbeat

Role of gap junctions in hearing

Recycling of K+ ions

Role of gap junctions in skin

Differentiation

Role of gap junctions in vascular cells

Contraction of smooth muscle cells

Role of gap junctions for nerves

Action potential

What is required for lens development

Cx43

What do mature fibre cells express

Cx46 and Cx50

What do Cx46 and cx50 needed for (2)

-Coupling of both peripheral and interior fibre cells

-maintaining lens transparency

What do mutations in Cx46 and Cx50 result in

Cataract formation

What do intracellular communication co ordinate

Diverse activities

What do intracelluar communication maintain

Homeostasis

What do local communication allow for

Cells of one tissue to act in a co ordinate manner

What do distance communication allow for

Co ordination between different organs

Name 2 ways cells communicate

Directly betweeen adjacent cells and chemical messengers

Example of cells communicating directly between adjacent cells

Gap junctions

Example of cells with chemical messengers

Paracrine, synaptic, endocrine

How does chemical messengers work

Releasing and responding to chemical messages

Give a charactertic of chemical messengers

Travel long or short distances from source to target cell

Example of synaptic

Neurotransmitter

How do neurotransmitters work

Released from nerve endings - diffuse across a short gap to act as a chemical messenger on target cell

What is a target cell

Plasma membrane of neurons, muscle or gland

Where are hormones released

From endocrine glands into bloodstream and travels to target organ

List steroid hormones

Cortisol, testosterone, oestrogen, progesterone

List non steroid hormones

Prostaglandins, insulin, FSH, glucagon, GnRh

What is the specificity of synaptic

Specific

What is the specificity of hormones

Specific

What is the range of synaptic

Short

What is the range of synaptic

Widespread

What is the response of synaptic

Rapid but short lasting

What is the response of hormones

Slow but long lasting

How much ATP does aerobic respiration produce

38ATP