3.2.1.1 - structure of eukaryotic cells

Question 1

what happens in complex multicellular organisms?

Answer 1

Eukaryotic cells become specialised for specific functions. The specialised cells are organised into tissues, the tissues into organs and the organs into systems.

Question 2

what is the structure and function of the cell surface membrane?

Answer 2

a phospholipid bilayer which controls the substances that can move in and out of the cell and allows cells to communicate via receptors on its surface

Question 3

function of nucleus?

Answer 3

contains genetic material (chromosomes made up of genes) so DNA can be stored, replicated and transcribed into mRNA

Question 4

structure of nucleus - nucleoplasm?

Answer 4

semi-solid fluid which contains nucleotides and enzymes needed for DNA/RNA synthesis

Question 5

structure of nucleus - nuclear envelope?

Answer 5

double membrane surrounding it made of two phospholipid bilayers (outer membrane continuous with endoplasmic reticulum), controls movement of materials and contains reactions

Question 6

structure of nucleus - nuclear pores?

Answer 6

allow passage of large molecules like ribosomes and mRNA out of nucleus, also means steroids and hormones can get in

Question 7

structure of nucleus - chromosomes?

Answer 7

lengths of protein-bound, linear DNA (DNA is tightly coiled so lots can be stored)

Question 8

structure of nucleus - nucleolus?

Answer 8

ribosomal RNA is joined together with associated proteins to assemble ribosomal subunits

Question 9

function of mitochondria?

Answer 9

site of aerobic stages of respiration so responsible for ATP production

Question 10

structure of mitochondria - matrix?

Answer 10

fluid which makes up most of mitochondria and contains enzymes for Krebs cycle (second stage of aerobic respiration)

Question 11

structure of mitochondria - cristae?

Answer 11

foldings of inner membrane to create large surface area for enzymes in oxidative phosphorylation (third stage of aerobic respiration which requires oxygen) to increase ATP production

Question 12

structure of mitochondria - mitochondrial DNA?

Answer 12

allows mitochondria to self-replicate so more can be made if cell’s energy needs to increase

Question 13

function of chloroplast?

Answer 13

site of photosynthesis in plants and algae

Question 14

structure of chloroplast - double membrane?

Answer 14

controls which molecules enter and leave

Question 15

structure of chloroplast - thylakoids?

Answer 15

fluid-filled membrane sacs containing chlorophyll and enzymes for light-dependent reactions

Question 16

structure of chloroplast - granum?

Answer 16

stacks of thylakoids allowing for efficient absorption of light

Question 17

structure of chloroplast - lamellae?

Answer 17

flat, thin parts of thylakoid membrane which join grana together so chemicals can pass between

Question 18

structure of chloroplast - stroma?

Answer 18

fluid-filled matrix where light-independent reactions take place (second stage of photosynthesis)

Question 19

structure of chloroplast - starch granules?

Answer 19

place for storing glucose produced in photosynthesis

Question 20

adaptions of chloroplasts?

Answer 20

grana create large surface area for light absorption, fluid of stroma contains enzymes for reaction, chloroplasts have DNA and ribosomes for quickly manufacturing proteins

Question 21

structure of Golgi apparatus?

Answer 21

stacks of membrane-bound, flattened sacs (cisternae) and sacks of small, rounded, hollow structures (vesicles)

Question 22

function of Golgi apparatus?

Answer 22

focus on processing and packaging molecules from ER - adds carbohydrates to proteins to form glycoproteins, produces secretory enzymes, transports, modifies and stores lipids, forms lysosomes

Question 23

function of lysosomes?

Answer 23

contain hydrolytic enzymes and bound by single membrane so involved in phagocytosis (enzymes digest bacteria), destroy organelles which are damaged or not functioning (enzymes digest), may transfer enzymes out of cell (exocytosis) to digest unwanted proteins/dead cells

Question 24

what are lysozymes?

Answer 24

enzymes found in lysosomes which aid the breakdown of proteins, polysaccharides, lipids, nucleic acids and old organelles

Question 25

structure of lysosomes - powerful digestive enzymes?

Answer 25

digest large molecules into small, soluble molecules

Question 26

structure of lysosomes - acidic interior?

Answer 26

enzymes in them have optimal pH which is acidic

Question 27

structure and function of ribosomes?

Answer 27

cytoplasmic granules found in cytoplasm or bound to RER, have small and large sub-unit, made of ribosomal RNA
some remain in cytoplasm and assemble proteins used inside cell, some attach to RER and assemble proteins used outside cell

Question 28

function of rough endoplasmic reticulum?

Answer 28

provides large surface area for synthesis of proteins and glycoproteins, provides pathway for transport of materials through cell

Question 29

structure of RER?

Answer 29

sheets of membranes which form flattened sacs called cisternae with ribosomes bound to membranes

Question 30

structure and function of smooth endoplasmic reticulum?

Answer 30

doesn’t have ribosomes bound to membranes, synthesises, stores and transports lipids and carbohydrates which can be modified in Golgi apparatus

Question 31

function of cell wall?

Answer 31

provides strength to plant cell (made of cellulose), permeable to water molecules

Question 32

structure of cell wall - middle lamella?

Answer 32

layer of material between plant cells made of polysaccharides, calcium and magnesium ions which acts as glue between cells

Question 33

structure of cell wall - algae?

Answer 33

contain polysaccharide cellulose and glycoproteins

Question 34

structure of cell wall - fungi?

Answer 34

made of polysaccharide chitin

Question 35

function of vacuoles?

Answer 35

large, permanent vesicles found in plant cells, cell sap has low water potential so water from cell moves into them creating pressure acting outwards so cell remains turgid to support plant

Question 36

structure of vacuoles - tonoplast?

Answer 36

membrane which surrounds plant cell vacuoles, helps control which chemicals enter and leave vacuole

Question 37

structure of vacuoles - cell sap?

Answer 37

weak solution of salts and sugars in vacuole, can contain poisonous chemicals to deter herbivores or coloured pigments in flowers to attract pollinators or waste chemicals produced by cell

Question 38

how might a plant leaf palisade cell have organelle adaptations for its function?

Answer 38

large number of chloroplasts - this allows for greater rate of light absorption for photosynthesis
Tall, thin shape - this means light can penetrate deeper before it reaches a cell wall which may absorb or reflect it, and the cells can be more densely packed

Question 39

how might a muscle cell have organelle adaptations for its function?

Answer 39

high density of mitochondria - the cristae and matrix contain the enzymes needed for aerobic respiration so large amounts of energy can be released for muscle contraction
layers of protein filaments - the layers can slide over each other to enable muscle contraction

Question 40

how might a white blood cell have organelle adaptations for its function?

Answer 40

high density of lysosomes - they release hydrolytic enzymes which can digest bacteria during phagocytosis