Studying cells

Question 1

eukaryotic definition

Answer 1

-nucleus
-membrane bound organelles

Question 2

nucleus general structure and function

Answer 2

-contains DNA
-largest organelle
-double membrane called the nuclear membrane
-nuclear pores allow for the passage of molecules
-nucleolus where ribosomal RNA is made
-ribosome proteins are synthesised in the nucleus but assembled outside the nucleus
-contains chromatin made up of DNA coiled around histones
-chromatin super condensed to form chromosomes

Question 3

mitochondrion

Answer 3

-site of ATP production by aerobic respiration
-double membrane
-inner membrane folded to form cristae SO high SA for attachment of ATP synthase enzymes
-matrix contains proteins,lipids,mitochondrial DNA and ribosomes

Question 4

rough endoplasmic reticulum

Answer 4

-highly folded membranes
-80s ribosomes
-RER synthesises and. transports proteins throughout the cell
-membrane folded into flattened sacks called cisternae
-RER joined to nucleus

Question 5

smooth endoplasmic reticulum

Answer 5

-recombines glycerol and fatty acids to make triglycerides.
-packages triglycerides into vesicles and transports them to the golgi apparatus

Question 6

ribosomes

Answer 6

-site of protein synthesis
-two subunits of a ribosome are made of a combination of long strands of rRNA
-dotted with ribosomal proteins.

Question 7

golgi apparatus

Answer 7

-sorts modifies and packages molecules
-golgi vesicles may be used to form lysosomes
-composed of flattened sacs of membranes
-sacs are fluid filled and pinch off smaller sacs (called vesicles) at their ends

Question 8

lysosomes

Answer 8

-used to hydrolyse damages and worn out organelles
-single membrane
-contain a large number of hydrolytic enzymes which are lysozymes in an acid solution which must be kept separate from rest of cell contents to prevent them from digesting organelles.

Question 9

cell surface membrane

Answer 9

-controls the passage of molecules in and out of the cell
-made up of phospholipids, specific transport proteins, and carbohydrates arranged into fluid mosaic model

Question 10

microvilli

Answer 10

finger like projections of the cell membrane
increase the surface area

Question 11

centrioles

Answer 11

-form a network of spindle fibres across the cell
-fibres pull apart chromosomes

Question 12

structures in a plant cell

Answer 12

-cellulose cell wall
-chloroplasts present
-large central vacuole
-carbohydrates stored as starch
-has no centrioles

Question 13

differences between plant vs animal

Answer 13

cell wall vs cellulose cell wall
chloroplasts present vs no chloroplasts
large central vacuole vs no large central vacuole
carbs stores as starch vs carbs stored as glycogen
has no centrioles vs has centrioles

Question 14

chloroplasts structure

Answer 14

granum which has stacks of thylakoid
thylakoid membrane contains chlorophyll for photosynthesis
stroma where photosynthetic reactions occur
starch grains is the energy storage molecule in plants

Question 15

DNA in plants

Answer 15

chloroplast DNA

Question 16

ribosomes in plants

Answer 16

70s ribosomes to make enzymes needed for photosynthesis

Question 17

function of chloroplasts

Answer 17

-absorbs light energy to converts it to chemical energy
-chemical energy is used to make carbohydrates from CO2 and H2O

Question 18

cellulose cell wall

Answer 18

-very strong which limits the volume of water that can move into the cell and stops osmotic lysis
-wall is permeable to most molecules
-cell walls of adjacent cells separated by a thin layer called the middle lamella
-has plasmodesmata, these are gaps in the cell walls that connect cell cytoplasm together to allow the easy movement of water soluble molecules

Question 19

bacterial cell characteristics

Answer 19

-do not have nuclei
-does not have membrane bound organelles

Question 20

prokaryotic cell vs eukaryotic cell

Answer 20

-circular DNA vs linear DNA
-contains no membrane bound organelles vs membrane bound organelles
-no true nucleus DNA is free vs a nucleus DNA contained within nuclear membrane
-70s vs 80s ribosomes
-some have capsule vs do not have a capsule
-cell wall made of meurin vs made cellulose

Question 21

viruses characteristics

Answer 21

-not cells as are not alive
-contains DNA or RNA
-protein coat called a capsid
-virus has attachment proteins
-lipid viral envelope

Question 22

resolution definition

Answer 22

ability to distinguish 2 objects that are close together

Question 23

relationship between wavelength and resolution

Answer 23

shorter the wavelength the better the resolution

Question 24

how the student could have used an eyepiece graticule to determine the mean diameter of stomata

Answer 24

-measure each stomata using an eye piece graticule
-calibrate the eyepiece graticule against a stage micrometer
-take at least 5 measurements and calculate a mean (more measurements are more accurate)

Question 25

TEM AO1

Answer 25

-pass through the specimen
-allows you to view organelles
-specimens fixed in resin and sliced extremely thin so must be dead
-specimens stained using heavy metals
-specimens must be in a vacuum so the specimen must be dead

Question 26

SEM

Answer 26

-specimens are not sliced
-electrons are bounced off the surface off the specimen
-3D image

Question 27

magnification equation

Answer 27

actual size= image size/magnification

Question 28

cell fractionation and differential centrifuge steps

Answer 28

-tissue is homogenised in a blender
-ice cold to reduce the action of enzymes that would digest organelles
-isotonic so prevents osmosis of water so cell lysis does not occur
buffered-stop pH changes which could denature enzymes
-mixture is then filtered to remove any large pieces of tissues
-centrifuged at high speed
-large organelles removes into a pellet
-supernatant is removed and centrifuged a higher speed for a longer time
-process is repeated until desired can be observed via a microscope