Cellular Organisation Flashcards

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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
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2
Q

Features of Eukaryotic (Animal) cells

A
  • Membrane bound organelles
  • Nucleus
  • Linear DNA
  • No cell wall
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3
Q

Features of plant cells

A
  • Membrane bound organelles
  • Chloroplasts
  • Cell wall
  • Large vacuole
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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
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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
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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
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7
Q

Role of membrane proteins in cell membrane

A
  • Integral (embedded in hydrophobic core) and peripheral (bound to surface)
  • Transport, signalling, recognition functions
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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
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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

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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
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11
Q

Function of Nucleus

A
  • Contains most of the cells genetic info
  • Synthesises mRNA for protein (Transcription)
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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
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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
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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
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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
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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
  1. Silent mutation
  2. Missense Mutation
  3. Nonesense Mutation
  4. 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
Q

Function of Golgi Apparatus

A
  • Further modification and folding of proteins/polypeptides
  • Packages and stores in secretory vesicles
26
Q

Structure & Function of Lysosomes

A
  • Bound by lysosomal membrane
  • Contains hydrolytic enzyme
  • Involved in phagocytosis
27
Q

Pathway of bound ribosomes to golgi apparatus

A
  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
Q

Secretory Pathway of Proteins

A
  1. Packaged in secretory vesicles -> buds off trans face of golgi
  2. Exocytosis occurs -> secretory vesicles fuse with membrane to release substances
29
Q

Membrane bound protein pathway

A
  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
Q

Lysosomal Enzymes/Proteins pathway

A
  1. Proteins modified to become hydrolytic enzymes
  2. Packaged in lysosomes -> buds off trans face
31
Q

Free ribosomes pathway

A
  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
Q

How does sickle cell anemia occur?

A

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