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Biology Hope > Cell Structure > Flashcards

Cell Structure Flashcards

1
Q

what is cell theory

A
  • both plant and animal tissue is composed of cells
  • cells are the basic unit of life
  • cells only develop from existing cells
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2
Q

what is dry mount

A
  • solid specimens are viewed
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3
Q

what is wet mount

A
  • specimens suspended in liquid
  • cover slip placed at an angle
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4
Q

what are squash slides

A
  • wet mount prepped first
  • lens tissue gently presses down cover slip
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5
Q

what are smear slides

A
  • edge of slide is used to smear the slide
  • thin even coating
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6
Q

what are positively charged dyes

A
  • crystal violet
  • methylene blue
  • attracted to negatively charged materials in the cytoplasm
  • stains cell components
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7
Q

what are negatively charged dyes

A
  • nigrosin and congo red
    -stays outside the cells leaving them unstained
  • stand out against the stained background
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8
Q

what is differential staining

A
  • distinguish between two types of organisms that would be hard to identify
  • differentiate between different organelles of a single organism
  • gram stain technique
  • acid fast technique
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9
Q

what is the gram stain technique

A
  • separates bacteria into gram positive and gram negative
  • crystal violet added to bacterial specimen then iodine added
  • slide washed with alcohol
  • gram positive retain crystal violet and stay blue
  • gram negative lose stain and counterstained with safarin dye to appear red
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10
Q

what is the acid fast technique

A
  • differentiate species of mycobacterium from other bacteria
  • lipid solvent carries carbolfuchsin dye into cells
  • cells washed with a dilute acid alcohol solution
  • mycobacterium retain carbolfuchsin stain
  • other bacteria lose the stain and stained with methylene blue
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11
Q

what are the stages of slide preparation

A

Fixing - chemicals used to preserve specimens in as near-natural state as possible

sectioning - specimens are dehydrated with alcohols and placed in wax/resin to harden

staining - shows different structures

mounting - specimens secured on a microscope and then a cover slip is placed

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12
Q

what is magnification

A

how many times larger the image is than the actual size of the object being viewed

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13
Q

what is resolution

A
  • the ability to distinguish between two close together points on the same specimen
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14
Q

how do you work with a scale bar

A
  • measure the actual length of the scale bar
  • divide it by the length is represents to work out the magnification
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15
Q

how do you calibrate a light microscope

A
  • line up the eyepiece graticule with stage graticule and focus the microscope
  • count the number of eyepiece divisions and note the number of micrometres
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16
Q

what are electron microscopes

A
  • uses a beam of electrons to illuminate the specimen
  • can show artefacts
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17
Q

what is a transmission electron microscope

A
  • beam of electrons is transmitted through a specimen and focused to produce an image
  • gives some contrast
    -2D image
  • resolving power of 0.5nm
  • x500 000 magnification
18
Q

what is a scanning electron microscope

A
  • beam of electrons is sent across the surface and is reflected off
  • resolving power 3-10nm
  • x100 000 magnification
19
Q

what are the features of an electron microscope

A
  • expensive
  • large and need installing
  • complex sample prep
  • sample prep may distort the sample
  • vacuum required
  • black and white images
  • x500 000 magnification
  • TEM =0.5nm SEM= 3-10nm
  • dead specimensw
20
Q

what are the features of a light microscope

A
  • inexpensive
  • small and portable
  • simple sample prep
  • sample prep doesn’t distort the sample
  • no vacuum
  • natural colour seen
  • x2000 magnification
  • 200nm
  • living or dead specimens
21
Q

what is a laser scanning confocal microscope

A
  • moves a single spot of focused light across a specimen
  • causes fluorescence from components
  • light emitted from the specimen is filtered through a pinhole aperture
  • only light radiated close to the focal plane is detected
22
Q

what is a eukaryote

A
  • any organism consisting of one or more cells that contain DNA in a membrane bound nucleus
23
Q

what is a nucleus

A
  • contains coded genetic information
  • DNA controls metabolic activities
  • DNA associated with histones to form chromatin
24
Q

what is chromatin

A
  • coils and condenses to form structures known as chromosomes
  • only visible when the cell is preparing to divide
25
Q

what is the nuclear envelope

A
  • protects DNA from damage
  • contains nuclear pores that allow molecules to move in and out
  • dense spherical structure
  • double membrane
26
Q

what is the nucleolus

A
  • produces ribosomes
  • composed of proteins and RNA
  • RNA produces ribosomal RNA and is combined with proteins to form ribosomes for protein synthesis
27
Q

what is the mitochondria

A
  • inner membrane is highly folded to form cristae and interior fluid called the matrix
  • inner membrane is coated in enzymes which catalyses the reactions of aerobic respiration
  • mitochondrial DNA
28
Q

What are vesicles

A
  • membranous sacs that have storage and transport roles
  • single membrane with fluid inside
  • used to transport materials inside the cell
29
Q

what are lysosomes

A
  • specialised vesicles containing hydrolytic enzymes
  • digestive enzymes to break down material
  • break down pathogens
  • role in apoptosis
30
Q

what is the cytoskeleton

A
  • network of fibres responsible for the shape and stability of a cell

Microfilaments - cell movement and contraction
Microtubules - structural support

31
Q

what is the endoplasmic reticulum

A
  • network of membranes enclosing flattened sacs called cisternae

Smooth
- lipid and carbohydrate synthesis and storage
Rough
- ribosomes bound to the surface
- synthesis and transport of proteins

32
Q

what are ribosomes

A
  • can be free floating in the cytoplasm or bound to the rough ER
  • no membrane
  • site of protein synthesis
33
Q

what is the golgi apparatus

A
  • compact structure
  • doesn’t contain ribosomes
  • modifies and packages proteins into vesicles
34
Q

what is the process of protein production

A
  • proteins synthesised from ribosomes bound on the rough ER
  • pass into cisternae and packaged into vesicles
  • vesicle moves to golgi apparatus via the cytoskeleton
  • vesicles fuse with golgi apparatus and proteins enter
  • proteins are structurally modified before leaving the golgi apparatus in vesicles
  • vesicles move towards and fuse with the cell membrane
  • vesicles release their contents by exocytosis
35
Q

what is the cellulose cell wall

A
  • provides rigidity to the cell
  • acts as a defence mechanism - protect the contents of the cell from invading pathogens
36
Q

what are vacuoles

A
  • membrane lined sacs in the cytoplasm containing cell sap
  • maintain a rigid framework for the cell
37
Q

what are chloroplasts

A
  • double membrane structure separated by stroma
  • internal network of flattened sacs - thylakoids
  • grana joined by lamellae
  • grana contains chlorophyll pigments
  • produces starch in the form of starch grains
  • contain their own DNA and ribosomes
  • internal membranes provide large surface area for photosynthesis
38
Q

what are prokaryotic cells

A
  • unicellular organism where the DNA isn’t contained in the nucleus
  • organelles aren’t membrane bound
39
Q

what are the features of prokaryotic cells

A
  • no nucleus
  • circular DNA
  • organelles not membrane bound
  • peptidoglycan cell wall
  • 70s ribosomes
  • has a cytoskeleton
  • reproduce by binary fission
  • unicellular
  • has a cell membrane
40
Q

what are the features of eukaryotic cells

A
  • has a nucleus
  • linear DNA
  • has membrane and non membrane bound organelles
  • chitin cell wall in fungi
  • cellulose cell wall in plants
  • 80s ribosomes
  • complex cytoskeleton present
  • reproduce sexually or asexually
  • unicellular or multicellular
  • cell membrane present

Biology Hope (26 decks)

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