Cell Organelles (A LEVELS)

Question 1

3 Rules of Cell Theory

Answer 1

1. New Cells come from pre-existing cells
2. Cells are the basic unit of life
3. All living things are composed of 1 or more cells

Question 2

Rough endoplasmic reticulum

Struc to FUNCTIONS

Answer 2

Struc:
- extensive Network of flattened membrane-bound sacs called cisternae
“RER & GB have a ‘cister’ named ‘Naeomi’ 🤞🤪”
#
FUNCTION:
- Provide increased surface area to volume ratio for rER ribosomes to be attached to maximise rate of polypeptide synthesis
- provide ample time & space for molecular chaperones to help fold protein into a 3D conformation
- proteins are also temp stored & packaging of proteins b4 exporting it from rER

_______ _______ _______
struc:
- 80S Ribosomes attached to cytosolic face of cisternae
##
Functions:
- rER as a site of protein synthesis

_______ _______ _______
struc
- rER cisternae extends from outer membrane of the nuclear envelope so it is close proximity to nucleus
###
Function
- messenger RNA can be immediately used as template for protein synthesis

Question 3

Smooth endoplasmic reticulum Struc & FUNCTION

Answer 3

Struc
- Network of interconnected membranous tubules
- More tubular than RER

Question 4

Nucleus Structure
(++ Nuclear envelope, Nuclear pores, nucleoplasm, chromatin, nucleolus. Struc + func)

Answer 4

Nucleus
- Spherical or ovoid
_________\____________________
Nuclear envelope:

• double membrane structure
• w/ 2 phospholipid bilayers
• Inner & outer membranes are continuous w/ each other
• the space in between them is the perinuclear space
• outer membrane is continuous w/ membrane of endoplasmic reticulum
• On nuclear envelope, there are nuclear pores
  _________\______________________
  Nuclear pores:
• Made of large protein complexes
• Allow small molecules to enter & exit nucleus

Eg: mRNA (Messenger ribonucleic acid) synthesised in the nucleoplasm can move into the cytoplasm for translation

_________\______________________
Nucleoplasm

• Semi-fluid that fills nucleus
  _________\______________________
  Chromatin
• DNA coils around histone proteins to form chromatin
• _________\______________________
  Nucleolus
• densely stained region in nucleus
• multiple can exist at once

STRUC:
- Contains instructions in DNA for synthesis of rRNA (ribosomal ribonucleic acid)

Question 5

Nucleus FUNCTION

Question 6

Centrioles FUNCTION

Question 7

Golgi body Struc & function

Answer 7

Struc
- Stack of flattened sacs called cisternae
- “RER & GB have a ‘cister’ named ‘Naeomi’ 🤞🤪”
- consists of cis/receiving face & trans/releasing face

Function
1. chem modifies proteins & lipids into glycoproteins & glycolipids respectively via glycosylation

2. GB temporarily stores substances synthesised by the cell
3. GB packages substances synthesised by the cell in vesicles that leave via the trans face of GB
   __
   - Stuff to be transported out of cell goes into secretory vesicles. They move to cell membrane along the cytoskeleton & fuse w/ cell membrane
   __
   - Hydrolytic enzymes go into vesicles called lysosomes that stay in the cytosol

Question 8

Ribosomes function

Question 9

Mitochondrion struc & function

Answer 9

Struc
- double membrane with a smooth outer membrane enclosing an extensively folded inner membrane
- the folds are called cristae
“Mito has a brother named ‘chris Tay’ “
_____
Function
-

Question 10

Chloroplast function

Question 11

Cell surface membrane function

Question 12

Struc of typical bacteria cell / PROKARYOTIC cell

Answer 12

• Small & unicellular
• has 70S ribosomes
• No nucleus
• *Circular DNA that is found in the cytoplasm in an area called the nucleoid
• No membrane bound organelles
• Has cell wall with peptidoglycan

Question 13

Types of prokaryotic cells and their differences

Answer 13

1. Gram-positive bacteria
   - More lipopolysaccharide
   Gram stain test:
2. Gram-negative bacteria
   - Less lipopolysaccharide
   Gram stain test: