organellees

Question 1

what are all the organelles in eukaryotic cells? (15)

Answer 1

The organelles we must know for eukaryotic cells are:
- cell surface membrane
- nucleus
- mitochondria
- chloroplasts
- golgi apparatus and vesicles
- lysosomes
- cytoskeleton
- centriole
- flagella
- cilia
- ribosomes
- rough and smooth ER
- Cell wall

Question 2

what is the structure and function of the nucleus?

Answer 2

STRUCTURE
- has a double membrane- nuclear envelope
- nuclear pores
- the nucleoplasm is made of granular jelly-like material
- contains chromosomes which are protein bound
- nucleolus- site of rRNA production and makes ribosomes- small dense sphere
FUNCTION
- site of DNA replication and transcription
- contains the DNA for each cell
- site of ribosome synthesis

Question 3

what is the structure and function of the flagella?

Answer 3

structure
- whip like structure
function
- mobility
- sensory organelle for chemical stimuli

Question 4

what is the structure and function of cilia?

Answer 4

structure
- hair-like projections out of cells
- made of two central microtubules, surrounded by 9 pairs (the 9+2 arrangement)
function
- can be mobile or stationary
- mobile cilia help move substances with a sweeping motion, e.g in the trachea or fallopian tubes
- stationary cilia are important in sensory organs

Question 5

what is the structure and function of centrioles?

Answer 5

centrioles
structure:
- made of microtubules
- occur in pairs to form the centrosome
function
- involved in the production of spindle fibres and organisation of chromosomes in cell division

Question 6

what is the structure and function of centrioles?

Answer 6

centrioles
structure:
- made of microtubules
- occur in pairs to form the centrosome
function
- involved in the production of spindle fibres and organisation of chromosomes in cell division

Question 7

what is the structure of the cytoskeleton?

Answer 7

structure
- network of fibres found within the cytoplasm of a cell
- made of microfilaments, microtubules and intermediate fibres
- microfilaments are found under the cell surface membrane, made of actin filaments, 8nm diameter
- intermediate fibres are stable scaffolding throughout the cell, 10nm diameter
- microtubules are a formation of cilia and flagella, 25nm diameter

Question 8

what is the function of the cytoskeleton?

Answer 8

function
- provides mechanical strength to cells.
- helps maintain strength and stability of cells.
- microfilaments are responsible for cell movement and dividing the cytoplasm during cell division.
- microtubules are responsible for creating a scaffolding-like structure, separates chromosomes in cell division, and moves organelles.
- intermediate fibres provide mechanical strength and holds organelles in place.

Question 9

what are the structures and functions of the smooth and rough ERs?

Answer 9

structure
- both have folded membranes called cisternae
- rough ER has ribosomes on the cisternae
function
RER- protein synthesis of extcretory proteins- proteins are transported through the rough ER and into secretory vesicles.
SER- synthesis and storage of lipids and carbohydrates

Question 10

what is the structure and function of the golgi apparatus and secretory vesicles?

Answer 10

structure
-folded membranes making cisternae
- secretory vesicles pinch off from the cisternae
function
- adds carbs to proteins to form glycoproteins
- produce secretory enzymes.
- secrete carbohydrates.
- transport, modify and store lipids.
- package and modify proteins.
- form lysosomes.
- finished products are transported to the cell surface membrane where they are released by exocytosis.

Question 11

what is the structure and function of lysosomes?

Answer 11

structure
- specialised vesicle- bag of hydrolytic enzymes.
function
- hydrolyse phagocytic cells
- completely break down dead cells
- exocytosis (release enzymes to outside of the cell)
- digest worn out organelles to reuse materials

Question 12

what is the structure and function of mitochondrion?

Answer 12

structure
- double membrane bound
- inner membrane called the cristae
- fluid centre called the matrix
- loop of mitochondrial DNA
function
- site or aerobic respiration
- site of ATP production
- contains DNA needed to code enzymes in respiration

Question 13

what is the structure and function of ribosomes?

Answer 13

structure
- made up of two subunits of protein and rRNA.
- 80s large ribosomes are found in eukaryotic cells. (25nm)
- 70S smaller ribosomes are found in prokaryotic cells, mitochondria and chloroplasts.
function
- site of protein synthesis.

Question 14

what is the structure and function of chloroplasts?

Answer 14

structure
- surrounded by a double membrane
- contains folded membranes which are embedded within pigments (these are called thykaloids)
- thylakoids stack up to form grana.
- fluid filled stroma contain the exymes for photosynthesis
- found only in plant cells
function
- site of photosynthesis

Question 15

what is the structure and function of the cell wall?

Answer 15

structure
- in plant and fungi cells
- in plants: made of microfibrils of the cellulose polymer
- in fungi: made of chitin (nitrogen containing polysaccharide)
function
- provide structural strength to the cell

Question 16

what is the structure and function of the plasma membrane?

Answer 16

structure
- found in all cells
- made of a phospholipid bilayer which has molecules embedded within/ attatched (proteins, carbs, cholesterol)
function
- controls the entrance and exit of molecules.

Question 17

what are the key differences between prokaryotic and eukaryotic cells?

Answer 17

• cells are much smaller
• no membrane-bound organelles
• smaller ribosomes (70S ribosomes)
• DNA is not contained within a nucleus- there is a singular DNA molecule free in the cytoplasm.
• the cell wall is made of peptidoglycan.
• they might calso contain plasmids, a slime capsule and flagella.

Question 18

what is the slime capsule and what does it do?

Answer 18

• the capsule is a slimy layer of protein.
• prevents the bacteria from dessicating and protects against the host’s immune system.