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A A A Level Biology > The final battle hehe :) > Flashcards

The final battle hehe :) Flashcards

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1
Q

why are organelles in eukaryotic cells membrane bound

A
  • it provides a distinct environment and therefore conditions for different cellular reactions
  • stops incompatable reactions
  • stops damage due to hydrolytic enzymes
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2
Q

what is the function of the nucleus

A
  • contains genetic material
  • controls metabolic activity of cell
  • where transcription and mRNA synthesised for protein synthesis

has a double membrane

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3
Q

what is the function of the nucleolus

A
  • responsible for producing ribosomes in the nucleus

- produces ribosomal RNA

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4
Q

what is the function of the nuclear envelope

A
  • protects the nucleus from the cytoplasm and contains nuclear pores
  • nuclear pores allows only certain molecules to move in and out such as mRNA
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5
Q

what is the function of the RER

A
  • ribosomes bound to the surface and are responsible for the synthesis and transport of proteins
  • connected to the membrane of the nucleus it is a network of membrane containing flattened sacs called cisternae
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6
Q

what is the function of the smooth ER

A

responsible for lipid and carbohydrate synthesis and storage

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7
Q

which kind of cells have higher numbers of RER

A

secretory cells such as those that secrete hormones or enzymes eg) nerve cells
more so than those that dont release proteins

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8
Q

what is the function of the Golgi apparatus

A

modifies proteins and packages them into vesicles

eg) lysosomes which stay in cell OR secretory vesicles that leave the cell

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9
Q

what is the function of ribosomes

A

site of protein synthesis
-made from RNA molecules made in nucleolus

mitochondria and chloroplasts also contain ribosomes and so do prokaryotic cells

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10
Q

what is the function of mitochondria

A
  • site of anaerobic respiration
  • release energy in the form ATP
  • energy is stored in complex organic molecules

how many mitochondria a cell has is a reflection of how much energy it uses

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11
Q

what is the function of lysosomes

A

they contain a hydrolytic enzyme which breaks down waste materials like old organelles

  • important in the immune system as they break down pathogens ingested by phagocytic cells
  • cell death and apoptsosis
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12
Q

why is the membrane surrounding a lysosome important

A

hydrolytic enzymes could damage cell structures so must be compartmentalised to stop damage

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13
Q

what is the function of chloroplasts

A

site of photosynethesis

  • green pigment chlorophyll absorbs sunlight
  • double membrane structures and fluid inside s called stroma
  • starch produced
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14
Q

what is the function of the plasma membrane

A

phospholipid bilayer embedded with proteins

-regulates the movement of substances in and out of cell and protects cell from surroundings

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15
Q

what is the function of centrioles

A

(two form a centrosome)
its a component of the cytoskeleton in eukaryotic cells apart from flowering plants and fungi
-the centrosome is involved in the assembly and organsisation of spindle fibres
-the are composed of microtubules

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16
Q

what is the cellulose cell walls function

A
  • made of cellulose a complex carbohydrate
  • freely permeable so substances to pass in/out
  • provide rigid structure (because contents of cell press against the wall) and give plant cell shape
  • protects cell from invading pathogens
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17
Q

what is the function of flagella

A

enable cell mobility

-also a sensory organelle which detects chemical changes in environment

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18
Q

what is the function of cillia

A
  • the rhythmically contract to waft substances and can be mobile or stationary
  • important in sensory organs like nose
  • cause substances and fluid next to cell to move
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19
Q

what are microfilaments

A
  • part of cytoskeleton
  • contractile fibres formed from the protein actin
  • these are reposnible for : cell movement, cell contraction during cytokinesis
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20
Q

what are microtubules

A

globular tubulin proteins polymerise to scaffold the struture which determines the shape of the cell
-act as conveyer belts to move organelles around the cell including vesicles for exocytosis

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21
Q

what is the function of vacuoles

A
  • membrane lined sacs in cytoplasm containing cell sap
  • important in maintaining tungor pressure, contents pushed up against cell wall for rigid structures
  • vacuoles in animal cells are small and not permanent
22
Q

the internal network of membranes form flattened sacks in chloroplasts called….

A

thylakoids

23
Q

granum are several thylakoids stacked but what joins them

A

lamellae

24
Q

describe the interelationship between organelles and the production and secretion of proteins

A

1) Proteins are sythesised on ribosomes bound to RER
2) pass onto its cisternae and are packaged into vesicles
3) these vesicles move to Golgi apparatus by cytoskeleton like microtubules
4) vesicles fuse with cis face of Golgi apparatus and proteins enter
5) proteins are structurally modified before leaving the Golgi by the trans face
6) vesicles move towards and fuse with the cell-surface membrane and leave by exocytosis

25
Q

what is the difference between magnification and resolution

A

magnification is how many times larger the image is than the actual object being viewed
resolution is how easy it is to distinguish between two points that are close together
differences in resolution and magnification can be achieved by a light microscope, transmission electron microscope and a SEMicroscope

for example resolution is increased using beams of electrons with wavelengths much shorter than light meaning objects smaller and closer together can be seen separately without diffraction blurring the image

26
Q

what is the magnification formula

A

magnification= image size / object size

27
Q

what is the purpose of staining

A

increase the constrast between structures/ organelles
specimens can be treated with multiple stains to show different structures

differential staining- used to distinguish between two types of organisms that would otherwise be hard to identify
can differentiate between different organelles of a single organism within a tissue sample

28
Q

what is gram-stain technique briefly

A

used to separate bacteria into two groups : gram positive and gram negative.

crstal violet dye is applied and washed with alcohol on sample gram positive retains this dye

29
Q

when preparing samples name 4 methods which could be used

A

dry mount- very thin slice of solid spec. cover slip over slide , thinness allows more light to pass through + more contrast

wet mount- cover slip placed on from an angle to minimise risk of air bubbles

squash slide- wet mount first prepped then lens tissue gently used to press down cover slip

smear slide- edge of slide used to smear sample to create thin even coating (for blood for example)

30
Q

how is an eyepiece graticule used

A

(relative sizes of divisions increases with magnification)

31
Q

how is a stage micrometer used

A

-very accurate scale in micrometers um

32
Q

how would you calibrate an objective lens

A

put stage micrometer in place and eyepiece graticule in the eyepiece

  • get scale on micrometer in clear focus
  • align micrometer with scale in the eyepiece
33
Q

what are the advantages and disadvantages of light microscopes

A

+easy to opperate
+cheaper
+observe living organisms

  • lower resolution
  • lower magnification
  • harder to view internal structures
34
Q

what are advantages and disadvantages of electron microscopes

A

+powerful magnification using electrons
+clearer image
+higher resolution

  • expensive
  • upkeep difficult
  • sensitive to magnetic fields
35
Q

what is fluoresence in terms of microscopy

A

absorbtion and re-radiation of light

its used as dye in Laser scanning confocal microscopy

36
Q

why do lasers provide illumination in LSCM

A

to increase the intensity of light across the specimen

37
Q

what is the purpose of the pinhole aperture

A
  • reduces blurring/ increased resolution

- eliminates scattered light/ light from outside focal plane

38
Q

how would you calibrate an eyepiece graticule and how is a calibration factor determined

A

-start w/ lowest power on objective lens
align scale on stage micrometer w/ scale on eyepiece graticule
take reading from both scales to find calibration factor

39
Q

describe the importance of the cytoskeleton

A
  • maintains shape and stability and provides support
  • changes shape of the cell
  • controls movement of vesicles
  • movement of chromosomes and mRNA
  • movement of flagella

microtubules, microfilaments, intermediate fibres

40
Q

what is an artifact

A

visible structural detail caused by the processing of the specimen but isnt a feature of the specimen eg bubbles trapped under slip during preparation

41
Q

why would you see more detail with an electron microscope than light microscope

A

electrons have shorter wavelengths than light waves.

higher magnification and better resolution

42
Q

how does electron microscope work

A

beam of electrons used to illuminate specimen and produces a magnification up to x500,000!!!

43
Q

TEM vs SEM

A

TEM- best resolution, see internal structure

SEM- electrons sent across surface and reflected electrons collected,
resolution not as good but 3D images can be collected

44
Q

what is LSCM

A

moves a sigle spot of focussed light across specimen by point illumination which causes fluoresnce from component’s labelled dye
emitted light from pinhole apperture
ONLY light close to focal plane is detected

45
Q

properties of water and its importance for living organsisms

A

-cohesive- so is able to be drawn up roots and xylem and also are more cohesive to each other than they are to air so there is a skin of surface tension
-solvent- because its polar solutes can be dissolved in it eg)cytosol in prokaryotes and eukaryotes)
- its a medium that can transport substances because its a solvent
-coolant- maintains constant temp as large amounts of energy are needed to overcome hydrogen bonding.
important as enzymes are only active in narrow temp ranges
-because ice floats it insulates water below for aquatic organisms.

46
Q

how do hydrogen bonds form in water molecules

A

unequal share of electrons between hydrogen and oxygen in a covalent bond
positive and negative regions attractand form hydrogen bonds which have weak interactions which break and reform constantly between water molecules

this bonding gives water its properties that support life

47
Q

which elements are in carbohydrates

A

C H O

48
Q

which elements are in lipids

A

C H O

49
Q

which elements are in proteins

A

C H O N S

50
Q

which elements are in nucleic acids

A

C H O N P

51
Q

what is the difference between a pentose and hexose monosaccharide

A

pentose is a group of monosaccahrides with 5 carbon

hexose is 6

A A A Level Biology (22 decks)

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