section 1: cell structure - topic 1: cells & organelles

Question 1

what are the 2 types of organism?

Answer 1

prokaryotes.
eukaryotes.

Question 2

what organelles are found in an animal cell?

Answer 2

cell surface membrane.
RER.
nucleus.
nucleolus.
SER.
lysosome.
ribosome.
nuclear envelope.
golgi apparatus.
cytoplasm.
mitochondrion.

Question 3

what organelles are found in a plant cell?

Answer 3

cell surface membrane.
RER.
nucleus.
nucleolus.
SER.
lysosome.
ribosome.
nuclear envelope.
golgi apparatus.
cytoplasm.
mitochondrion.

cell wall with plasmodesmata (‘channels’ for exchanging substances between adjacent cells).
vacuole (compartment that contains cell sap).
chloroplasts (organelles involved in photosynthesis)

Question 4

what is the cell surface membrane?

Answer 4

the membrane found on the surface of animal cells & just inside the cell wall of plant cells & prokaryotic cells.
mainly made of lipids and proteins.

Question 5

what is the function of the cell surface membrane?

Answer 5

regulates the movement of substances into and out of the cell.
has receptor molecules on it, which allow it to respond to chemicals like hormones.

Question 6

what is the cell wall?

Answer 6

a rigid structure that surrounds plant cells.
mainly made of cellulose (carbohydrate).

Question 7

what is the function of the cell wall?

Answer 7

supports plant cells.

Question 8

what is the nucleus?

Answer 8

a large organelle surrounded by a nuclear envelope (double membrane) which contains many pores.
the nucleus contains chromatin (which is made from DNA & protein) & often a structure called the nucleolus.

Question 9

what is the function of the nucleus?

Answer 9

controls the cells activities (by controlling the transcription of DNA).
DNA contains instructions to make proteins.
the pores allow substances (i.e. RNA) to move between the nucleus & the cytoplasm.
the nucleolus makes ribosomes.

Question 10

what is a lysosome?

Answer 10

a round organelle surrounded by a membrane with no clear internal structure.

Question 11

what is the function of a lysosome?

Answer 11

contains digestive enzymes - these are kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down worn out components of the cell.

Question 12

what is a ribosome?

Answer 12

a very small organelle that either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum.
made up of proteins & RNA.
not surrounded by a membrane.

Question 13

what is the function of a ribosome?

Answer 13

the site where proteins are made.

Question 14

what is the RER?

Answer 14

a system of membranes enclosing a fluid-filled space.
surface is covered with ribosomes.

Question 15

what is the function of the RER?

Answer 15

folds & processes proteins that have been made at the ribosomes.

Question 16

what is the SER?

Answer 16

similar to the RER, but with no ribosomes.

Question 17

what is the function of the SER?

Answer 17

synthesises & processes lipids.

Question 18

what is a vesicle?

Answer 18

a small fluid-filled sac in the cytoplasm, surrounded by a membrane.

Question 19

what is the function of a vesicle?

Answer 19

transports substances in and out of the cell (via the plasma membrane) and between organelles.
some are formed by the golgi apparatus or the endoplasmic reticulum, whilst others are formed at the cell surface.

Question 20

what is the golgi apparatus?

Answer 20

a group of fluid-filled, membrane-bound, flattened sacs.
vesicles are often seen at the edges of the sacs.

Question 21

what is the function of the golgi apparatus?

Answer 21

processes & packages new lipids & proteins.
also makes lysosomes.

Question 22

what is a mitochondrion?

Answer 22

usually oval-shaped.
has a double membrane - the inner one is folded to form structures called Cristal.
the matrix is inside - contains enzymes involved in respiration.

Question 23

what is the function of mitochondria?

Answer 23

the site of aerobic respiration, where ATP is produced.
mitochondria are found in large numbers in cells that are very active and require a lot of energy.

Question 24

what is a chloroplast?

Answer 24

a small, flattened structure found in plant cells.
surrounded by a double membrane & has membranes inside called thylakoid membranes.
^ stacked up in some parts of the chloroplast to form grant.
^ grant are linked together by lamellae - thin, flat pieces of thylakoid membrane.

Question 25

what is the function of a chloroplast?

Answer 25

the site where photosynthesis takes place.
some parts of photosynthesis happen in the grana & other parts happen in the stroma ( a thick fluid found in chloroplasts).

Question 26

what is a centriole?

Answer 26

small, hollow cylinders made of microtubules (tiny protein cylinders).
found in animal cells, but only some plant cells.

Question 27

what is the function of a centriole?

Answer 27

involved with the separation of chromosomes during cell division.

Question 28

what is cilia?

Answer 28

small, hair-like structures found on the surface membrane of some animal cells.
in cross-section, they have an outer membrane & a ring of 9 pairs of protein microtubules inside, with a single pair of microtubules in the middle.

Question 29

what is the function of cilia?

Answer 29

the microtubules allow the cilia to move.
this movement is used by the cell to move substances along the cell surface.

Question 30

what is a flagellum?

Answer 30

flagella on eukaryotic cells are like cilia but longer.
they stick out from the cell surface membrane & are surrounded by the plasma membrane.
inside they’re like cilia too - 2 microtubules in the centre & 9 pairs around the edge.

Question 31

what is the function of a flagellum?

Answer 31

these microtubules contract to make the flagellum move.
flagella are used like outboard motors to propel cells forward.