MODULE 2 : eukaryotic cell structure

Question 1

eukaryotic cell

Answer 1

complex cell with a true nucleus

Question 2

nucleus

Answer 2

contains linear DNA which is associated with proteins called histones
controls the cells activities

Question 3

nucleolus

Answer 3

involved in the synthesis and assembly of ribosomes

Question 4

nuclear envelope

Answer 4

double membrane with nuclear pores

pores allow large molecules such as mRNA to pass in and out of the nucleus

Question 5

ribosomes

Answer 5

site of protein synthesis and may either be free or bound to the ER
made up of two subunits: the large and small subunit which are both made up f equal amounts of protein and RNA

Question 6

smooth endoplasmic reticulum

Answer 6

made up of a dense system of membrane tubes with fluid filled space called cisternae
site of lipid and steroid synthesis and processing
found in liver cells and intestinal epithelial cells and some hormonal secreting cells

Question 7

rough endoplasmic reticulum

Answer 7

made up of a dense system of membrane tubes with fluid filled space called cisternae
has ribosomes attached to it
involved in protein synthesis and secretion
found in enzyme secreting cells

Question 8

Golgi apparatus

Answer 8

a series of flattened vesicles in stacks which receive protein in vesicles from RER
form secretory vesicles which bud off to transport proteins to diff parts of the cell for secretion

Question 9

mitochondria

Answer 9

site of aerobic respiration
oval shaped and surrounded by double membrane
inner membrane is folded, folds are called cristae
inside of mitochondria is the matrix which contains other enzymes involved in aerobic respiration

Question 10

lysosomes

Answer 10

a round organelle with no clear internal structure
contains digestive systems involved in the breakdown of large molecules
abundant in secretory cells and phagocytic white blood cells

Question 11

plasma membrane

Answer 11

also known as cell membrane
controls the exit and entry of molecules
has receptor molecules on its surface

Question 12

centrioles

Answer 12

small hollow cylinders containing rings of microtubules
synthesise spindle fibres during mitosis
involved in separation of chromosomes during cell division
always found in pairs

Question 13

cilia

Answer 13

small hair like structures found on the surface of some cell membranes
contain microtubules in a 9,2 arrangement
able to move substances along the cell surface e.g. oviducts and trachea

Question 14

flagellum

Answer 14

like cilia but longer

microtubules contract to make flagellum move e.g. sperm

Question 15

cytoskeleton

Answer 15

the internal structural units of a cell
supports cell’s organelles and keeps them in position
assist in transporting material around the cell
maintains cell shape

Question 16

microtubules

Answer 16

form the scaffold of cilia and flagella which aids cell movement
polymers of tubulin and form part of the cytoskeleton and maintains shape of cell

Question 17

chloroplasts

Answer 17

site of photosynthesis
surrounded by double membrane
contains a series of stacked membranes called thylakoid membranes

Question 18

vacuoles

Answer 18

membrane bound sacs containing dilute solutions
surrounding membrane is called tonoplast
plant cells usually have larger permanent ones and animal cells have smaller, temporary vacuoles
contains cell sap
important in keeping cell rigid/turgid

Question 19

cell wall

Answer 19

rigid structure surrounding plant cell
made of fibres of cellulose held together by a matrix of protein, hemicellulose and pectin
supports the cell, maintaining turgidity
prevents the cell from bursting when under osmotic pressure