Eukaryotes

Question 1

comparison to prokaryotes

Answer 1

more complex ultrastructure than prokaryotic cells

Question 2

what is the cytoplasm of eukaryotes divided up into

Answer 2

membrane-bound compartments called organelles

Question 3

what does animal cell have that plant cells don’t

Answer 3

Animal cells contain centrioles and some have microvilli while plant cells do not

Question 3

what key structures do animal and plant cells share

Answer 3

Membrane-bound organelles, including a nucleus

Larger ribosomes known as 80S ribosomes

Question 4

Microvilli

Answer 4

Microvilli are folded regions of the cell surface membrane that increase cell surface area for absorption

Question 5

What do plant cells have that animal cells don’t

Answer 5

Plant cells have a cellulose cell wall, large permanent vacuoles, and chloroplasts while animal cells do not

Question 6

cell surface membrane

Answer 6

controls the exchange of materials between the internal cell environment and the external environment
The membrane is described as being partially permeable
Cell membrane is formed from a phospholipid bilayer

Question 7

The nucleus

Answer 7

relatively large and separated from the cytoplasm by a double membrane called the nuclear envelope, which has many pores

Question 8

What does nucleus consist of

Answer 8

chromatin: material from which chromosomes are made. Chromosomes are made of sections of linear DNA tightly wound around proteins called histones

nuclear envelope: nucleus is relatively large and separated from the cytoplasm by a double membrane.Nuclear pores are important channels for allowing mRNA and ribosomes to travel out of the nucleus

nucleolus: darkly stained regions, sites of ribosome
production

Question 9

What is the mitochondria

Answer 9

The site of aerobic respiration
are just visible with a light microscope

Question 10

Structure of mitochondria

Answer 10

double-membrane with the inner membrane folded to form structures called cristae

The matrix of mitochondria contains enzymes needed for aerobic respiration, producing ATP

Small circular pieces of DNA, known as mitochondrial DNA, and ribosomes are also found in the matrix

These are needed for replication of mitochondria before cell division

Question 11

Ribosomes

Answer 11

free organelles in the cytoplasm of all cells or as part of the rough endoplasmic reticulum

They are not surrounded by a membrane
Each ribosome is a complex of ribosomal RNA (rRNA) and proteins

80s ribosomes are found in eukaryotic cells
70s ribosomes are found in prokaryotes, mitochondria, and chloroplasts
Ribosomes are the site of translation

Question 12

What is rough and smooth endoplasmic reticulum

Answer 12

RER is formed from folds of membrane continuous with the nuclear envelope
The surface of RER is covered in ribosomes
The role of the RER is to process proteins made on the ribosomes and FOLDS THE PROTEIN

SER is also formed from folds of membrane but its function is distinct from the RER, being involved in the production, processing and storage of lipids, carbohydrates and steroids
SER does not have ribosomes on its surface

Question 13

Golgi apparatus
structure
how is it distinguished from SER
role

Answer 13

flattened sacs of membrane similar in appearance to the smooth endoplasmic reticulum

The Golgi apparatus is sometimes known as the Golgi body

The Golgi can be distinguished from the SER by its regular, stacked appearance; it can be described as looking like a wifi symbol!

The role of the Golgi apparatus is to modify proteins and lipids before packaging them into Golgi vesicles
The vesicles then transport the proteins and lipids to their required destination

Question 14

Lysosome

Answer 14

Lysosomes are specialist forms of vesicle which contain hydrolytic enzymes
The role of lysosomes is to break down waste materials such as worn-out organelles,
Lysosomes are used extensively by cells of the immune system

Question 15

Centrioles

Answer 15

made of hollow fibres knows as microtubules

Microtubules are filaments of protein that can be used to move substances around inside a cell, as well as to support the shape of a cell from the inside

Two centrioles at right angles to each other form a centrosome which organises the spindle fibres during cell division

Question 16

How is the RER related to protein synthesis

Answer 16

Ribosomes on the RER produce proteins that can be secreted out of the cell or become attached to the cell surface membrane

Proteins that have been passed into the lumen of the rough endoplasmic reticulum are folded and processed here

Question 17

How is Golgi apparatus related to protein synthesis

Answer 17

Processed proteins from the RER are transported to the Golgi apparatus in vesicles which fuse with the Golgi apparatus, releasing the proteins into the Golgi
The Golgi apparatus modifies the proteins, preparing them for secretion

These proteins are Exported, Put into lysosomes, Delivered to other membrane-bound organelles

Question 18

Steps

Answer 18

nucleolus makes ribosomes for protein synthesis in RER
The nucleus then manufactures mRNA needed by ribosomes to make proteins
Ribosomes in RER make proteins
RER processes the proteins which are sent in vesicles to golgi body
golgi body further processes modify and send in vesicles to plasma membrane
to fuse with fuse with membrane to secrete protein exocytosis

Question 19

Difference eukaryotes and prokaryotes

Answer 19

(eukaryotic organisms) have membrane-bound organelles

(eukaryotic organisms contain) a named membrane- bound organelle

size of ribosomes larger than in prokaryotes

(eukaryotic organisms contain) DNA that is {linear / associated with (histone) proteins}. Composed of a single, double-stranded DNA molecule in the form of a loop or circle

(eukaryotic organisms) do not contain plasmids (in cytoplasm)

Question 20

How can you identify if an organelle is Golgi apparatus

Answer 20

membrane bound sacs / cisternae
curved / flattened ;
no ribosomes

Question 21

explain why enzymes that are folded incorrectly by rER cant carry out function

Answer 21

tertiary will be different so cant bind to substrate and form enzyme substrate complex so cant catalyse reaction

Question 22

role of golgi apparatus

Answer 22

(Golgi apparatus) { modifies / processes } protein ;
2. details of modification e.g addition of carbohydrate chains, trimming of carbohydrate / reference to glycoprotein;
3. (Golgi apparatus) packages proteins in (secretory) vesicles;
4. for (export from cells by) exocytosis / eq;
5. reference to lysosomes;