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biology > 2.1.1: cell structure > Flashcards

2.1.1: cell structure Flashcards

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1
Q

how do you use a light microscope?

A
  • arms used to clip the slide in place
  • rotate turret with objective lens to the lowest (x4 mag)
  • looking through eye piece, use fine adjustment knob until a clearer image can be viewed
  • rotate the objective lenses and select x10 power, followed by the fine knob
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2
Q

what are the equations to calculate magnification, image size and actual size?

A
  • magnification = image size / actual size
  • image size = magnification x actual size
  • actual size = image size / magnification
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3
Q

what is the difference between magnification and resolution?

A

magnification is the number of times greater the image is greater than the object, whereas resolution is the ability to distinguish between two objects that are very close together

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4
Q

why do we stain cells and how does it work?

A

provides contrast between different parts of the cell as different parts take up different volumes of stain

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5
Q

how do you prepare a dry mount?

A

specimen is cut into thin slices (sectioned) then covered with a cover slip e.g hair, pollen, insects

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6
Q

how do you prepare a wet mount?

A

specimen is cut into thin slices (sectioned) then covered with a drop of liquid such as water, oil or stain, then cover with a cover slip

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7
Q

what are squash slides?

A

where the sample is squashed between the slide and the cover slip (a type of wet mount) e.g. stain that is used for soft tissue such as root tip

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8
Q

what are smear slides?

A

where another slide is used to smear the sample across the slide e.g. used for a thin layer of liquid e.g blood

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9
Q

What are the advantages and disadvantages of using a light microscope?

A

+ easy to use
+ colour image
+ cheap and accessible
- low magnification and resolution
- can’t see organelles like ribosomes

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10
Q

what is a scanning electron microscope and how does it work?

A

where electrons spread out on the surface of the specimen, then reflected back off the surface (wavelength of the electrons is shorter than light)

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11
Q

what are the advantages and disadvantages of using a scanning electron microscope?

A

+ forms 3D shape
+ don’t need it to be a thin sample
- done in a vacuum = no live samples can be used
- can’t see the internal structures
- lower magnification and resolution than a transmission electron microscope

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12
Q

how does a transmission electron microscope work?

A

uses a beam of electrons that pass through the specimen

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13
Q

what are the advantages and disadvantages of using a transmission electron microscope?

A

+ better resolution
+ shorter wavelength of electrons than light
+ allows internal structures to be seen
- can’t look at living organisms
- doesn’t form colour image
- 2D
- needs to be an ultra thin specimen to allow electrons to pass through

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14
Q

how does a laser scanning confocal microscope work?

A
  • fluorescent dye is added to the specimen
  • laser beam (light) focused on part of the cell
  • light fluorescents from different depths within the cell
  • a pinhole sits in front of the detector
  • pinhole eliminates out of focus light
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15
Q

What are the advantages and disadvantages of using a laser scanning confocal microscope?

A

+ much higher resolution than light microscope
+ can view objects (organelles) from inside the cells
- more expensive than light microscope
- lower resolution than transmission electron microscopes

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16
Q

what are the stains crystal violet and methylene blue used for and why?

A

organelles as they are both positively charges components that attract negatively charged materials

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17
Q

what is iodine used for?

A

plant cells e.g starch

18
Q

what are the stains nigrosin and congo red used for?

A

outside layer of the cells

19
Q

structure and function of the nucleus

A

structure = contained within a double membrane (nuclear envelope) that allows molecules in and out

function = contains coded genetic information in the form of DNA molecules (which is linear and tightly wound around hist one proteins to form chromosomes), controls metabolic activities of the cell

20
Q

structure and function of the nucleolus

A

structure = composed of RNA and ribosomes

function = responsible for producing ribosomes (by making RNA)

21
Q

structure and function of ribosomes

A

structure = spherical 20nm, free floating or attached to the exterior of the RER

function = sight of protein synthesis (contains the hydrolytic enzyme lysosome

22
Q

structure and function of the rough endoplasmic reticulum (RER)

A

structure = network of membranes enclosing flattened sac (known as cisternae), folds of membranes that are connected to the outer membrane of the nucleus

function = ribosomes bound to the surface and is responsible for transport and synthesis of proteins

23
Q

structure and function of the smooth endoplasmic reticulum (SER)

A

structure = network of membranes enclosing flattened sac (known as cisternae), folds of membranes that are connected to the outer membrane of the nucleus

function = responsible for lipid and carbohydrate synthesis and storage (makes packages in vesicles)

24
Q

structure and function of the mitochondrion

A

structure = has a double membrane, the inner membrane is highly folded form of structure called cisternae fluid interior (matrix), contains enzymes used for aerobic respiration

function = site of final stage of cellular respiration, where energy is stored in the bonds of complex organic molecules. It is made available for the cell to use by production of ATP (adenosine tri - phosphate)

25
Q

structure and function of a centrosome

A

structure = composed of microtubules (two associated centrioles form the centrosome)

function = the centrosome is involved in the assembly and organisation of the spindle fibres during cell division

26
Q

structure and function of a vesicle

A

structure = single membrane with fluid inside

function = transport material inside the cel

27
Q

structure and function of a lysosome

A

structure = a specialised form of vesicle that contains hydrolytic enzymes

function = breaks down waste material in cells + breaks down pathogens

28
Q

structure and function of the plasma membrane

A

structure = consists of a layer of lipid bilayer that is partially permeable

function = regulates the transport of material entering and exiting the cell

29
Q

structure and function of the golgi apparatus

A

structure = compact structure of cisternae, does NOT contain ribosomes

function = modifies proteins and ‘packages’ them into vesicles. These may be secretary vesicles (if protein is designed to leave the cell) or lysosome (if it stays INSIDE the cell)

30
Q

structure and function of the cytoskeleton

A

structure = consists of…
1. microfilament for cell movement and contraction (during cytokynesis)
2. microtubules - like scaffolding that determines the shape, and acts like a tracer for movement of organelles
3. intermediate fibres - provides mechanical strength to cells and helps maintain integrity

function = necessary for shape, providing mechanical strength to cells, aiding transport within cells and enabling cell movement

31
Q

structure and function of flagella

A

structure = (whip like) used to move the cell, act as a tail

function = enable cell mobility, can be used as a sensory organelle detecting chemical changes in cell’s environment

32
Q

structure and function of cilia

A

structure = hair-like with two central microtubules and a wheel of microtubes in a pair (9+2 arrangement) there are two types stationary and mobile

function = 1. stationary > usually involved in sensing e.g. the nose
2. mobile > used to move items e.g. mucus

33
Q

structure and function of chloroplasts

A

structure = they have a double membrane structure with fluid inside (called stroma), they have an internal network of membranes (flattened sacs called thylakoids) several stacked to make granum. Pl = grana also contain chlorophyll pigments where photosynthesis takes place

function = where photosynthesis takes place, in a plant cell

34
Q

structure and function of a cell wall

A

structure = made up of cellulose (complex carbohydrate) made through b- glucose. It is freely permeable to allow substances to pass in/out

function = supports both the individual cell and the plant as a whole, protects the contents of the cell from invading pathogens

35
Q

structure and function of a vacuole

A

structure = membrane lined sacs in the cytoplasm containing cell sap, the membrane (tonoplast) is selectively permeable

function = important in the maintenance of turgor so that inside the cell wall (push against it) and keep the cell turgid

36
Q

what is the cell structure of a prokaryotic cell?

A
  • no nucleus = free floating DNA - sometimes plasmid
  • different type of ribosomes e.g. smaller 70s ribosomes
  • capsule goes around the outside - defence against the host cell
  • cell wall made up of peptidoglycan (also known as murein)
  • pilli = increase surface area, some have flagella
37
Q

which organelles do plant cells have that animal cells don’t?

A

cell wall, permanent vacuole, chloroplasts and peroxisomes

38
Q

which organelles do animal cells have that plant cells don’t?

A

temporary vacuoles, lysosomes and centrisomes

39
Q

how is a protein produced and exported?

A
  • a single strand copy of gene is made of RNA = mRNA
  • the mRNA leaves the nucleus via a nuclear pore
  • travels to a ribosome on the rough endoplasmic reticulum
  • the ribosome reads the code on the mRNA to build the protein out of amino acids
  • protein travels through the cisternae until it reaches the end of the RER
  • protein is “pinched off” in a vesicle to travel to the golgi apparatus
  • vesicle fuses to the golgi apparatus where is is modified and packaged into another vesicle
    this vesicle containing the protein travels to the cell surface membrane
  • vesicle fuses to the cell surface membrane and is released by exocytosis
40
Q

what are some similarities and differences between eukaryotic and prokaryotic cells?

A

similarities = both have ribosomes, DNA, (some) cell walls and cytoplasm

differences = eukaryotic cells have cell bound organisms, a nucleus, make up plant and animal cells and are multicellular, while prokaryotic cells have plasmids, flagellum, pili, make up bacteria cells and are single-cellular

biology (10 decks)

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