cell structure eukaryotic

Question 1

plasma cell surface membrane

Answer 1

regulates the movement of substances into and out of the cell. has receptor molecules on it which allow it to respond to chemicals (e.g. hormones)

Question 2

cell wall

Answer 2

• rigid structure that surrounds plant cells and supports them
• made up of cellulose (carbohydrate)

Question 3

what is the nucleus made up of and what does it do

Answer 3

controls the cell’s activities
- nuclear envelope
- nucleolus
- nuclear pores
- chromatin (made from DNA and proteins)

Question 4

nucleolus

Answer 4

• makes ribosomes
• composed of proteins and RNA
• RNA is produced to rRNA which combines with proteins to form ribosomes

Question 5

nuclear envelope

Answer 5

• double membrane
• protects DNA inside from damage in the cytoplasm

Question 6

nuclear pores

Answer 6

• allow molecules to move into and out of the nucleus
• DNA is too large to leave so it is transcribed to RNA molecules which can leave via nuclear pores

Question 7

lysosome

Answer 7

• specialised forms of vesicles
• contains digestive enzymes
• these are kept separate from cytoplasm by the membrane
• they are used to digest invading cells, to break down worn out cell components

Question 8

ribosome

Answer 8

• made up of proteins and RNA
• not surrounded by a membrane
• site of protein synthesis

Question 9

rough endoplasmic reticulum

Answer 9

• system of membranes enclosing a fluid-filled space
• surface covered in ribosomes
• folds and processes proteins that have been made at ribosomes

Question 10

smooth endoplasmic reticulum

Answer 10

• system of membranes enclosing a fluid-filled space
• synthesises and processes lipids and carbohydrates

Question 11

vesicle

Answer 11

• fluid-filled sac in the cytoplasm, surrounded by a membrane
• transports substances into and out of a cell and between organelles
• some are formed by the golgi apparatus or endoplasmic reticulum, or cell surface

Question 12

golgi apparatus

Answer 12

• group of fluid-filled, membrane-bound, flattened sacs.
• vesicles are often at the edges of the sacs
• processes and packages new lipids and proteins
• makes lysosomes

Question 13

mitochondria

Answer 13

-double membrane
- outer membrane
- inner membrane folds into cristae structures
- fluid interior is called the matrix
- site of aerobic respiration where ATP is produced
- large numbers found in active cells that require a lot of energy

Question 14

chloroplast

Answer 14

• flattened structure found in plant cells
• double membrane
• contains thylakoid membranes inside which are stacked up to form grana (contain chlorophyll)
• grana are linked by lamelle (thin, flat pieces of thylakoid membrane)
• stroma is the thick fluid found in the cell
• site of photosynthesis
• photosynthesis happens in grana and stroma

Question 15

centriole

Answer 15

• small, hollow cylinders made of microtubules
• animal cells, only some plant cells
• involved with the separation of chromosomes during cell division
• 2 associated centrioles form a centrosome
• centrosome is involved in assembly and organisation of spindle fibres during cell division

Question 16

cilia

Answer 16

-small, hair-like structures on the surface membrane of some animal cells
- in cross section, they have an outer membrane and a ring of 9 pairs of microtubules, with 2 microtubules in the middle
- microtubules allow the cilia to move
- this moves substances along the cell surface

Question 17

flagellum

Answer 17

• on eukaryotic, they are like cilia but longer
• stick out from the sell surface
• 2 microtubules in the centre and 9 pairs around the edge
• microtubules contract to make flagellum mover
• flagella are used like outboard motors to propel cells forward

Question 18

vacuoles

Answer 18

• membrane bound (tonoplast) sacs in the cytoplasm containing cell sap
• tonoplast is selectively permeable
• large permanent vacuoles are important in the maintenance of turgor

Question 19

cytoskeleton

Answer 19

• in the cytoplasm of eukaryotic cells
• network of fibres necessary for the shape and stability of the cell
• organelles are held in place by it and their movement is controlled by it

its 3 components are
- microfilaments
- microtubules
- intermediate fibres

Question 20

microfilaments

Answer 20

• protein actin
• contractible fibres
• responsible for cell movement and cell contraction during cytokinesis

Question 21

microtubules

Answer 21

• globular tubulin proteins polymerise to form tubes
• form a scaffold-like structure which determines cell shape
• act as tracks for movement of organelles around the cell
• make up spindle fibres (segregation of chromosomes in cell division)

Question 22

intermediate fibres

Answer 22

• give mechanical strength to cells
• help maintain cell integrity