cell structure & function

Question 1

what is the cell theory

Answer 1

1. cells are the smallest unit of life
2. all living things are made up of one or more cells
3. all cells arise form pre-exisiting cells by cell division

Question 2

2 types of cells

Answer 2

prokaryotes and eukaryotes

Question 3

describe the 2 types of cells

Answer 3

prokaryotes:
- lacks membrane-bound organelles
- lacks a nuclues so DNA is free-lying
eukaryotes:
- contains membrane-bound organelles
- has a nucleus enclosed by a nuclear envelope
- DNA is usually organised into numerous chromosomes

Question 4

stucture and function of eukaryotic cells

Answer 4

structure:
- it is surrounded by a CSM and a cell wall
- CSM encloses and maintains a fluid environment called the cytoplasm
function:
organelles allow for compartmentalisation.
1. membrane surrounding cell organelles enable separate compartments to be formed inside cell, thereby allowing specialised metabolic pathways to take place
2. hydrolytic enzymes in lysosomes require lower pH from rest of cell to function optimally
3. different reactions can take place (eg. krebs cycle in mitochondrial matrix/ calvin cycle in the stroma of chloroplast) as reactants and enzymes of a metabolic pathwat can be kept tgt
4. membrane bound organelles with inner membrane that are highly folded allow for more transport proteins/enzymes/receptors to be embedded, leading to increase SA for metabolic reactions to occur efficiently
5. outer and inner mitochondrial membrane enclose the intermembrane space in mitochondria to allow accumulation of H+, resulting in formation of proton gradient which is used for chemical synthesis of ATP

Question 5

structure (3) and functions (2) of nucleus

Answer 5

stucture:
- it is the largest organelle and can be seen easily under a light microscope
- spherical in shape and measures an average of 5µm in diameter
- contains DNA, where most genes that control the activities of cell are found
functions:
- to contain cell’s DNA
- directs cellular activities (direct protein synthesis, to direct DNA replication during cell division)