Cells

Question 1

define ‘eukaryotic cell’.

Answer 1

a cell that contains membrane bound organelles and genetic material in the form of a nucleus.

Question 2

define ‘ultrastructure’

Answer 2

the detailed internal structure of a cell

Question 3

describe 3 differences between a eukaryotic cell and a prokaryotic cell.

Answer 3

1. eukaryotes have membrane bound organelles such as mitochandria
2. eukaryotic cells have a nucleus which contains DNA, prokaryotes have a circular loop of DNA in their cytoplasm.
3. prokaryotic cells have DNA in the form of plasmids outside of the nucleus, eukaryotic cells don’t have extra DNA.

Question 4

define ‘prokaryotic cell’

Answer 4

a cell that contains no membrane bound organelles and no nucleus.

Question 5

describe the process of production and trafficking of proteins.

Answer 5

1. the mRNA is created in the nucleus
2. the mRNA leaves the nucleus through a nuclear pore and attaches to a ribosome
3. the ribosome in turn attaches to the membrane of the rough ER and synthesizes the protein.
4. the membrane of the rough ER creates a vesicle around the protein and it travels to the golgi apparatus
5. the vesicle fuses with the golgi apparatus’ membrane and the golgi body modifies the protein.
6. the golgi then forms a secretory vesicle around the protein and it leaves the cell via the cell surface membrane.

Question 6

name the three components of the cytoskeleton.

Answer 6

• actin filaments
• intermediate filaments
• microtubules

Question 7

name the functions of the cytoskeleton in the cell.

Answer 7

ACTIN FILAMENTS:
-help change the shape of a cell
-stabilize cell shape
-help change the shape of a cell
INTERMEDIATE FILAMENTS
-help change the shape of a cell
hep divide cytoplasm during cell division
MICROTUBULES
-form cilia and flagella (9+2 arrangement)
-divide chromosomes during cell division
-help move larger molecules.

Question 8

state 3 differences and 3 similarities between a plant and animal cell.

Answer 8

similarities:
- both have a nucleus
- both have mitochondria to produce ATP
- both have cell surface membranes
differences:
-plant cells have large permanent vacuoles
-plant cells have a cell wall, animal cells do not
-plant cells have chloroplasts for photosynthesis

Question 9

describe and name the parts of a chloroplast.

Answer 9

a chloroplast has a double membrane
the inner membrane forms disks called thylakoids, these stack up to form grana.
the spaces in between grana are called stroma

Question 10

describe and name the parts of a mitochondrion.

Answer 10

a mitochondrion has a double membrane, the inner membrane forms folds called the matrix.
each fold creates a gap called a cristae.

Question 11

describe the structure and function of flagella.

Answer 11

structure - rigid, rotating, helical shaped tail. made from an element of the cytoskeleton called microtubles. arranged in a 9+2 arrangement.
function - used to propel the cell

Question 12

describe the structure and function of cilia.

Answer 12

structure - short, hair like structures that protrude from the cell surface membrane - they have the same internal structure as flagella.
function - move in a wave like motion to move things across the cell membrane or move the cell itself.

Question 13

describe the structure and function of the cell wall.

Answer 13

structure - a mesh like structure surrounding plant cells made of cellulose fibres. 
function - supports the cell when turgid also provides protection for the cell.

Question 14

describe the structure and function of centrioles.

Answer 14

structure - a short bundle of microtubules held at right angles to each other.
function - forms a spindle like structure that chromosomes travel along during nuclear division.

Question 15

describe the structure and function of the plasma membrane.

Answer 15

structure - a thin, phospholipid bilayer surrounding a cell
function - partially permeable, allows substances to pass in and out of the cell.

Question 16

describe the structure and function of chloroplasts.

Answer 16

structure - a double membrane bound organelle consisting of stacks of thylakoids called grana linked by intergranal lamallae, surrounded by stroma.
function - contain chlorophyll and are the site of photosynthesis in plant cells which is the process of turning light into energy.

Question 17

describe the structure and function of lysosomes.

Answer 17

structure - spherical sacs containing digestive enzymes surrounded by a single membrane.
function - digest worn out organelles and remove vacuoles after the process of phagocytosis.

Question 18

describe the structure and function of mitochondria.

Answer 18

structure - a double membrane bound organelle that has a folded inner membrane creating cristae which form a matrix.
function - the site of respiration in cells which produces  ATP which powers most of the processes in the cell that require energy.

Question 19

describe the structure and function of ribosomes.

Answer 19

structure - small organelles not bound by a membrane, consisting of of two subunits made of proteins and RNA.
function - synthesize proteins

Question 20

describe the structure and function of the golgi apparatus.

Answer 20

structure - a stack of membrane bound, flattened sacs.
function - modifies proteins and packages them into vesicles which are then secreted from the cell.

Question 21

describe the structure and function of the smooth ER.

Answer 21

structure - membrane bound sacs called cisternae, with no ribosomes attached.
function - involved in the synthesis of lipids.

Question 22

describe the structure and function of the rough ER.

Answer 22

structure - stacks of membrane bound sacs called cisternae. continuous with the outer nuclear membrane. they often have ribosomes on the cytoplasmic side.
function - allow ribosomes to attach to their membrane, which then forms vesicles around the newly synthesized proteins.

Question 23

describe the structure and function of the nuclear envelope.

Answer 23

structure - a double membrane surrounding the nucleus, with fluid in between them. it also contains pores.
function - encloses the nucleus. contains pores which allow substances such as RNA to pass out of the nucleus.

Question 24

describe the structure and function of the nucleolus.

Answer 24

structure - a dense, spherical structure within the nucleus.
function - makes RNA and ribosomes.

Question 25

describe the structure and function of the nucleus.

Answer 25

structure - contains chromatin, surrounded by the nuclear envelope.
function - houses cells genetic material. chromatin contains the instructions for making proteins.