Function and structure of organelles

Question 1

Structure and Function of the Nucleus?

Answer 1

Structure:
• Surrounded by double membrane - nuclear envelope
• Pores in nuclear envelope
• Nucleolus doesnt hare a membrane around it contains RNA , site of ribosome production
• Chromatin, the genetic material consisting of DNA.

Function:
• control centre of cell, stores organism’s genome, transmits genetic information, instructions for protein synthesis.

Question 2

Structure and Function of Rough ER?

Answer 2

Structure:
* series of flattened sacs (cisternae) enclosed by a membrane
* coated in ribosomes

function:
* cisternea forms channels for transporting substances e.g proteins to Golgi apparatus
* large surface area for ribosomes which assemble amino acids into proteins = Protein synthesis

Question 3

Structure and Function of Smooth ER?

Answer 3

Structure:
• Cisternae that are continuous with nuclear membrane
• no ribosomes on surfuce.

function:
• Synthesis and store lipids and carbohydrates.

Question 4

Structure and Function of Golgi Apparatus?

Answer 4

Structure:
• Folding membranes making cisternae.
• secretory vesicles pinch off from cisternae.

function :
• Modifies proteins e.g adds carbohydrates to form glycoproteins,
secretory enzymes.
• finished products transported to cell surface in vesicles where it fuses with membrane and is released
• form lysosomes

Question 5

Structure and Function of Lysosomes?

Answer 5

Structure:
* Bags of digestire enzymes - can contain 50 different enzymes.

function:
* Digest worn out organelles for reuse of materials

Question 6

Structure and Function of Mitochondria?

Answer 6

Structure:
• double membrane, inner chamber cristae
• fluid centre - mitochondric matrix, loop of mitochondria DNA, ribosomes inside

Function.
• Site of aerobic respiration, ATP production (energy)
• DNA to code for enzymes needed in respiration.

Question 7

Structure and Function of ribosomes?

Answer 7

Structure:
• made of two sub-units of protein and rRNA
• 80 S- large ribosomes in eukaryotic cells
• 70 S - smaller ribosomes in prokaryotes, mitochondna and chloroplast

Function:
• Protein synthesis site.

Question 8

Structure and Function of Chloroplast?

Answer 8

Structure:
•surrounded by double membrane, have own DNA
• thylakoids (folded membranes)
• fluid with enzymes needed for photosynthesis

function:
• Site of photosynthesis

Question 9

Structure and Function of Flagella?

Answer 9

Structure:
• Whip like structure

function
• mobility and sometimes as a sensory organelle for chemical stimuli.

Question 10

Structure and Function of Cillia?

Answer 10

Structure :
• Hair like projections out of cells

function:
• helps move substances in sweeping motion (mobile)
• important in sensory organs e.g nose (stationany)

Question 11

Structure and Function of Centrioles?

Answer 11

Structure:
• made of microtubules, in pairs to make centrosome

function:
• involved in production of spindle fibre and organisation of chromosomes in cell division

Question 12

Structure and Function of Cytoskeleton?

Answer 12

Structure:
• network of fibres found within cytoplasm
• consists of microfilaments, microtubules, intermediate fibres

function:
• mechanical strength, shape, stablty, • microfilaments - cell movement
• microtubules - scaffold like structure

Question 13

Structure and Function of Cell Wall?

Answer 13

Structure:
• Plants - made of cellulose
• Fungi - made of chitin (nitrogen containing polysaccharide)
•Bacteria - peptidoglycan

Function:
•provide structual strength to the cell

Question 14

Structure and Function of Plasma membrane?

Answer 14

Structure:
• found in all cells - cell surface membrane
• Phospholipid bilayer - molecules embeded e.g proteins, carbonyarates, cholesterol

Function:
• Controls what enters and exits the cell.