Organelle structure and function

Question 1

Define ultrastructure

Answer 1

internal structure which suits the cell to its function

Question 2

Define Eukaryotic

Answer 2

distinct nucleus

membrane bound organelles

Question 3

What is the function of the nucleus?

Answer 3

Site of DNA replication and transcription
Contains genetic code
controls the cells activity

Question 4

What is the size of the nucleus?

Answer 4

10-20 um

Question 5

List and describe the 5 parts of the nucleus and their function

Answer 5

nuclear envelope= double membrane continuous with the ER. Controls the entry/exit of materials and contains the reactions talking place

Nuclear pores= allows large molecules(mRNA) to exit the nucleus, typically 3000 per nucleus, 40-100nm diameter

Nuclear pore= granular, jelly like substance that is the bulk of the nucleus

Chromosomes= protein bound linear DNA

Nucleolus= manufactures ribosomal RNA and ribosomes

Question 6

What is the function of the mitochondria?

Answer 6

produces ATP

site of aerobic respiration

Question 7

What is the size of the mitochondria?

Answer 7

1-10um

Question 8

Describe the three parts of the mitochondria

Answer 8

Double membrane= controls entry and exit of materials

Cristae= extension of the inner membrane which provides a large SA for the attachment of enzymes and proteins

Matrix= rest of mitochondria/ contains protein, lipid, ribosomes, DNA (controls production of own proteins), enzymes involved in respiration

Question 9

Function of ribosomes

Answer 9

site of protein synethesis

Question 10

what are the two types of ribosomes

Answer 10

*80S = eukaryotes, 25nm in diameter

70S= Prokaryotic, mitochondria , chloroplasts

Question 11

Chloroplast function and size

Answer 11

carry out photosynthesis

2-10um long and 1um in diameter

Question 12

Name the three main features of the chloroplasts

Answer 12

Chloroplast envelope= double membrane that controls entry/exit

Grana= stacks of up to 100 thylakoids( contain chlorophyll)/ where the first stage of photosynthesis occurs

Stroma= fluid-filled matrix where the second stage of p. occurs

Question 13

How is the chloroplast adapted to their function?

Answer 13

grana membrane= large SA for the attachment of enzymes/ electron carriers/chlorophyll. These chemicals are attached to the membrane in a highly ordered fashion

fluid of the stroma possess all the enzymes needed to make the sugars in the 2nd stage of photosynthesis

contains both DNA and ribosomes so they can easily manufacture some proteins needed for photosynthesis

Question 14

Describe the structure of the cell wall and how that links to their function

Answer 14

consist of microfibrils of polysaccharide cellulose, embedded in a matrix. The cellulose microfibrils have considerable strength.

Question 15

Describe the features of the cell wall

Answer 15

consist of polysaccharides eg cellulose

thin layer called middle lamella which marks the boundary between adjacent cell walls and cements them together.

Question 16

Explain the functions of the cell wall

Answer 16

to provide mechanical strength

allow water to pass along it so contributes to the movement of water through the plant.

Question 17

What are algae and fungi cell walls made up of?

Answer 17

Algae= cellulose or glycoproteins or a mix

fungi=mix of chitin, glycan and glycoproteins

Question 18

Define vacuole

Answer 18

a fluid-filled sac bounded by a single membrane

Question 19

Describe vacuole structure

Answer 19

single membrane around vacuole = tonoplast

contains solution of mineral salts, sugars, amino acid , wastes, sometimes anthocyanins

Question 20

Name the functions of the vacuole

Answer 20

support herbaceous plants/ parts of wood plants by making cells turgid

sugars and amino acids act as a temporary food store

pigment may colour petals to attract pollinating insects

Question 21

Describe the Endoplasmic reticulum structure

Answer 21

3d system of sheet like membranes in the cytoplasm continuous with the outer nucleus membrane. The membrane encloses a network of tubules and cisternae

Question 22

Name the two types of Endoplasmic reticulum and what is their difference?

Answer 22

Rough and smooth

Rough has ribosomes on its outer surface, smooth does not and is often more tubular in appearance

Question 23

Describe the function of the RER

Answer 23

provide large SA for (glyco) protein synthesis

Question 24

Describe the function of the SER

Answer 24

synthesis,store and transport lipids and carbohydrates

Question 25

Describe the structure of the Golgi apparatus

Answer 25

similar to SER ( 3d sheet like membrane that encloses a network of tubules and cisternae

Question 26

Describe the action sequence that commonly occurs in the Golgi apparatus

Answer 26

protein/lipid sequenced by ER passed through Golgi apparatus

Golgi apparatus modifies protein adding nonprotein components.
Labels and sorts the protein/lipid and transported in a Golgi vesicle to be exocytosed

Question 27

Name the functions of the Golgi apparatus

Answer 27

add carbohydrates to proteins to form glycoproteins

produce secretory enzymes

secrete carbohydrates

transport, modify and store lipids

form lysosomes

Question 28

Name the functions of the lysosomes

Answer 28

hydrolyse materials ingested by phagocytic cells

release enzymes to the outside of the cell to destroy material around the cell

digest worn out organelles so the useful chemicals they are made from can be re-used

completely breakdown cells after they have died

Question 29

Where are lysosomes abundant?

Answer 29

In secretory cells

eg. epithelial and phagocytic cells

Question 30

Describe the process of proteins being made

Answer 30

ER/Ribosomes synthesis protein
Golgi Apparatus modifies protein from ER by adding non protein components, labels and sorts the proteins before being pinched off in a vesicle and the end of the cisternae
The vesicles then leave out of the cell membrane via exocytosis