Cellular Organisation Flashcards
1
Q
Features of prokaryotic (bacteria) cells
A
- Absence of membrane bound organelles
- Circular DNA in nucleoid
- Contains ribosomes, cell wall, cytoplasm
- Flagella for movement
2
Q
Features of Eukaryotic (Animal) cells
A
- Membrane bound organelles
- Nucleus
- Linear DNA
- No cell wall
3
Q
Features of plant cells
A
- Membrane bound organelles
- Chloroplasts
- Cell wall
- Large vacuole
4
Q
What is the meaning of fluid mosiac model?
A
- Mosaic -> Phospholipid bilayer, collage of different proteins -> embedded in fluid matrix of lipid bilayer
- Fluid -> lipids and proteins diffuse freely within bilayer
- Flip-flop, lateral, rotational
5
Q
Role of phospholipids in cell membrane
A
- Hydrophilic heads -> interact with aqueous outer environment (cytoplasm or tissue fluid)
- Hydrophobic tails -> face inwards creating hydrophobic core
6
Q
Role of steroids/cholesterol in cell membrane
A
- Regulates membrane fluidity and permeability at different temperatures
- Prevents packing at low temp -> more fluid
- Restrains movement at high temp -> less fluid
7
Q
Role of membrane proteins in cell membrane
A
- Integral (embedded in hydrophobic core) and peripheral (bound to surface)
- Transport, signalling, recognition functions
8
Q
What is hypertonic?
A
- Outside is higher water potential as compared to cell, water moves into cell
- Turgid plant cell
- Lysed red blood cell
9
Q
What is hypotonic?
A
Outside is lower water potential as compared to cell, water moves out of cell
- Plasmolysed plant cell
- Shrivelled red blood cell
10
Q
Structure of Nucleus
A
- Largest organelle in animal cell
- Double membrane nuclear envelope -> nuclear pores on surface
- Dense nucleolus region -> rRNA synthesis
- Aqueous matrix -> contains most genetic info
11
Q
Function of Nucleus
A
- Contains most of the cells genetic info
- Synthesises mRNA for protein (Transcription)
12
Q
Structure and Function of Ribosomes
A
- Two locations -> bound ribosomes to the Rough Endoplasmic Reticulum (RER) -> synthesise polypeptides for secreted/membrane/lysosomal proteins
- OR free ribosomes suspended in cytoplasm -> synthesise polypeptides for proteins used in cell
- Translation of mRNA into protein
13
Q
What is the role of mRNA
A
- Template for translation of polypeptide strand
- Conveys sequence of codons to code for specific amino acids
- Contains start and stop codons to signal beginning and termination of translation
14
Q
Process of DNA transcription
A
- DNA template strand used to synthesise mRNA -> complementary to template strand
- DNA non-template strand same as mRNA, replace T with U
- In nucleus
15
Q
Process of Polypeptide translation
A
- mRNA codons read by ribosomes to synthesise amino acids
- Peptide bonds formed between amino acids to form polypeptide chain
- Start and stop codons signal beginning and termination fo translation