Cell structure

Question 1

Nucleus?

Answer 1

Contains DNA which codes for protein synthesis
Components: Nucleolus, nuclear envelope, nuclear pore, nucleoplasm, chromatin, inner and outer membrane

Question 2

nuclear envelope?

Answer 2

separates DNA from cytoplasm, double membrane

Question 3

Nuclear pore?

Answer 3

Allows for the transport of mRNA out of the nucleus

Question 4

Nucleolus?

Answer 4

Site of the synthesis of rRNA and ribosomes (can be more that 1)

Question 5

Ribosomes?

Answer 5

2 subjnits made of ribosomal RNA (rRNA): small subunit + large subunit. Made of protein and rRNA. Can be free or attached to rough endoplasmic reticulum

Question 6

nuclearplasm?

Answer 6

granular, jelly-like material

Question 7

chromosomes?

Answer 7

protein bound, linear DNA

Question 8

Rough and Smooth endoplasmic reticulum

Answer 8

Both have folded membranes called cisternae
RER- the ribosomes on the cisternae make it rough, protein synthesis here
SER- no ribosomes, synthesis and store lipids and carbohydrates

Question 9

golgi apparatus?

Answer 9

Cisternae: secretiry vesicles or lysosomes pinch off of cisternae carrying finished product
Molecules can be ‘labelled’ as to their destination (using receptors)

Question 10

Functions of golgi apparatus?

Answer 10

Add carbohydrates to proteins: glycoprotein, transport, store and chemically modify lipids/ proteins, produce secretory enzymes, secrete carbohydrates, form lysosomes , packaging of newly produced proteins in Golgi vesicles

Question 11

lysosome?

Answer 11

Sack of digestive enzymes

Question 12

Function of lysosome?

Answer 12

Digest worn out organelles for reuse of materials, completely break down dead cells (phagocytes or body cells (autolysis)), release enzymes to outside of the cell to destroy material (exocytosis)

Question 13

Mitochondria structure?

Answer 13

Double membrane: outer + folded inner which is called cristae separated by inter membrane space, inner solution=mitochondrial matrix, small circular DNA, 70S ribosomes

Question 14

mitochondria function?

Answer 14

site of aerobic respiration, site of ATP production, the DNA loops code for enzymes required for respiration

Question 15

80s/70s ribosomes?

Answer 15

80s = large ribosomes found in eukaryotic cells
70s= smaller ribosome found in prokaryotic cells, mitochondria and chloroplasts

Question 16

vacuole?

Answer 16

Fluid filled, surrounded by a single membrane called tonoplast
Makes cell turgid to provide support, temporary store of sugars and amino acids, can contain pigments to attract pollinators

Question 17

thylakoids?

Answer 17

Folded membranes embedded with pigment in chloroplasts (chlorophyll), stacked× 2-100 = granum, between them= lamella

Question 18

chloroplasts components?

Answer 18

Double membrane, thylakoid/ geranium, lamella, stroma, 70s ribosomes, starch granules, small DNA circles

Question 19

chloroplasts stroma

Answer 19

Stroma= fluid, contains enzymes for reactions which are light independent

Question 20

Why cristae?

Answer 20

Increase SA on which part of respiration process occurs

Question 21

size and shape of mitochondria

Answer 21

cylinder shaped, 1-10 um in diameter: being a cylinder reduces diffusion distance between edge and centre, increases efficiency of aerobic respiration

Question 22

vesicles as vacuoles (animal cells)

Answer 22

Contractile vacuole: small, membrane contained organelle. Maintains osmotic pressure

Question 23

cell wall?

Answer 23

made of cellulose in plants and chitin in fungi

Question 24

plasma membrane?

Answer 24

phospholipid bilayer+ molecules embedded within or attached to outside e.g carbohydrates, proteins, cholesterol

Question 25

centrioles?

Answer 25

Two hollow cylinders perpendicular to each other, used in spindle formation in cell division (They release long, stiff fibres called micro tubules that split the cell appart during cell division). Not in plant cells.

Question 26

chloroplasts structure?

Answer 26

2-10 um diameter, 1um thick

Question 27

plant cell wall?

Answer 27

cellulose microfibrils in the polysaccharide matrix pectin, prevents osmotic lysis (cell bursting), strength and support, freely permeable to water

Question 28

Plasmodesmata ?

Answer 28

narrow thread of cytoplasm that passes through the cell walls of adjacent plant cells.

Question 29

function of plasmodesmata

Answer 29

exchange large organic materials via cytoplasmic streaming, allow communication between adjacent cells

Question 30

function of RER?

Answer 30

synthesis and transportation of proteins. The RER is continuous with the nuclear membrane.

Question 31

function of SER?

Answer 31

Synthesis and storage of lipids and carbohydrates

Question 32

what are all the membranes made of?

Answer 32

Phospholipids which are very dynamic: this is what allows membranes to be pinched off but also to merge with other membranes to release products

Question 33

what does 1 gene code for?

Answer 33

Order of amino acids in 1 poly peptide

Question 34

where does mRNA bind after leaving nucleus through nuclear pore?

Answer 34

To ribosomes on rough endoplasmic reticulum

Question 35

what happens to polypeptide chain after being synthesised at RER?

Answer 35

Moves through cisternae of RER, away from nucleus, towards cell membrane

Question 36

what is mRNA

Answer 36

copy of a segment of DNA

Question 37

various sites/ stages of protein synthesis (simple)

Answer 37

mRNA in nucleus, mRNA on ribosomes on RER, polypeptide through RER, protein in transport vesicles, enter golgi body, become lysosomes or secretery vesicles, excretion of protein through exocytosis

Question 38

Exocytosis?

Answer 38

mass transport of molecules out of the cell, process requires ATP, synthesised by mitochondria during aerobic respiration

Question 39

how do lysosomes break down worn out organelles?

Answer 39

Membrane of lysosome murges with that of organelle, releasing digestive enzymes into organelle. Hydrolyses organelle

Question 40

Autolysis?

Answer 40

Break down of dead cells: several lysosomes burst within a cell releasing digestive enzymes which hydrolise the cell

Question 41

How do lysosomes partake in phagocytosis

Answer 41

Pathogens are engulfed by white blood cells and become trapped in a vacuole within the cell. Membrane of lysosome merges with that of vacuole, emptying digestive enzymes into vacuole to digest pathogen

Question 42

describe the interrelationship between the nucleus, RER, golgi body and plasma membrane

Answer 42

synthesizing proteins

Question 43

plasma membrane

Answer 43

controls entry and exit of molecules in and out of the cell. It is selectively permeable

Question 44

Chromatin?

Answer 44

In nucleus, coils of DNA bound to protein. During cell division, condenses into chromosomes

Question 45

Benefit of the structure of granum?

Answer 45

Large SA, efficient for trapping light energy

Question 46

specific benefits of cells having organelles/ membranes?

Answer 46

Isolates harmful substances like digestive enzymes, concentrates enzymes in a smaller space for higher RoR, allows multiple reactions to occur simultaneously without interference (compartemenatlisation), allows the functions of mitochondria and chloroplasts, increases SA for enzyme attachment