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
16
Q
DNA level mutations
A
- Base pair substitution
- Base pair insertion
- Base pair deletion
- Three base-pair insertion/deletion
17
Q
Polypeptide Level mutations
A
- Silent mutation
- Missense Mutation
- Nonesense Mutation
- Frameshift Mutation
18
Q
What is a silent mutation?
A
Does not change amino acids specified by codons -> no change to protein structure
19
Q
What is a nonsense mutation?
A
Change in amino acid(s) resulting in EARLY STOP CODON -> shortened polypeptide
20
Q
What is a frameshift mutation?
A
Change in reading frame of nucleotide sequence -> Drastic change in sequence of amino acids -> Change in protein structure
21
Q
Structure of the Endoplasmic Reticulums
A
- Membrane of ER continuous with nuclear envelope -> encloses ER cisternae
- Internal space filled with endoplasmic matrix -> cisternae space/lumen
- Rough ER -> appears rough due to studded ribosomes
- Smooth ER -> absence of ribosomes
22
Q
Function of Rough ER
A
- Ribosomes studded synthesise polypeptides
- Primary structure folded into secondary and tertiary structure -> in cisternae space
- Packages proteins into transport vesicles
23
Q
Function of Smooth of ER
A
- Synethesis of lipids
- Carbohydrate metabolism
- Detoxification
24
Q
Structure of golgi apparatus
A
- Flattened membrane sacks -> cisternae
- Cis face -> recieves transport vesicles from ER
- Trans face -> packages products into secretory vesicles and vesicles bud off trans face
25
Function of Golgi Apparatus
- Further modification and folding of proteins/polypeptides
- Packages and stores in secretory vesicles
26
Structure & Function of Lysosomes
- Bound by lysosomal membrane
- Contains hydrolytic enzyme
- Involved in phagocytosis
27
Pathway of bound ribosomes to golgi apparatus
1. Bound ribosomes -> synthesise polypeptides from amino acids
2. Polypeptides released into cisternae space of RER
3. In cisternae space -> primary structure folded into Second, Tertiary structure
4. Packaged into transport vesicles, buds off RER -> Fuses with cis face of golgi apparatus
5. Chemically modified in golgi
28
Secretory Pathway of Proteins
1. Packaged in secretory vesicles -> buds off trans face of golgi
2. Exocytosis occurs -> secretory vesicles fuse with membrane to release substances
29
Membrane bound protein pathway
1. Integrated into secretory vesicle membrane -> buds off trans face of golgi
2. Fuses with cell membrane -> membrane bound proteins part of cell membrane
30
Lysosomal Enzymes/Proteins pathway
1. Proteins modified to become hydrolytic enzymes
2. Packaged in lysosomes -> buds off trans face
31
Free ribosomes pathway
1. Free ribosomes -> synthesise polypeptide chains from amino acids
2. In the cytoplasm -> primary structure folds itself into secondary and tertiary structure
3. Protein used in the cell
32
How does sickle cell anemia occur?
Sickle Cell Anemia
- Single base pair substitution of Adenine to Thymine -> glutamic acid replaced by valine
- Alters the shape of red blood cells
- Lack of oxygen in bloodstream
