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OCR A-level Biology Module 2: Foundations in Biology > Cell Strucure > Flashcards

Cell Strucure Flashcards

Everything from microscopes to cellular organelles, you gotta know it all inside out!

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1
Q

dont mention magnification here….

What is Resolution in microscopy?

A

This is the ability to distinguish between 2 separate points, clearly

NOT THE SAME AS MAGNIFIATION, Do not get confused…

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2
Q

What is Magnification in microscopy?

A

The number of times larger an image appears, as compared to the size of the real object.

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3
Q

Think Formula triangle……

Equation for Magnification

A

Magnification = Image Size / Real Size

Using IMA Formula triangle for easy use!

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4
Q

What techniques are used to see unstained and live specimens?

A
  • Light interference (rather than light absorption. It eliminate halos and extra light. )
  • Dark background
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5
Q

What is a Logarithimic Scale?

think of powers….

A
  • This is a scale is used to represent data that spans a wide range of values, making it easier to visualise and compare.
  • Instead of increasing linearly, a logarithmic scale increases by orders of magnitude. This means each step on the scale represents a multiplication of the previous value, often by a factor of 10

usefull to compare exponetially growing / increasing relative values…

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6
Q

Give the main features of Laser Scanning Confocal Microscope

give the mag, resolution, images and use

A
  • Uses a laser to create an image, pixel per pixel onto a digital screen, with high contrast
  • MAGNIFICATION: x2000 and more
  • RESOLTION: Greater than Opticals
  • Image?&raquo_space; Sharp, 3D, coloured image with depth selectivity
  • Used mostly by med professionals

Depth Selectivity: Ability to focus on different depths of an organism

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7
Q

you should know what this stands for

Give the features of a TEM.

give the give the mag, resolution, images and use

A
  • Uses a beam of electrons, in a VACCUM!
  • MAGNIFICATION: X2,000,000
  • RESOLUTION: 0.2nm
  • Image?&raquo_space; 2D, black and white thinly sliced images, detecting electrons passing through specimen
  • Specimen must be dehydrated, stained with metal salts, always!

Electrons passing through specimen = can see internal cell structures!!

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8
Q

you should know what this stands for

Give the features of a SEM.

give the give the mag, resolution, images and use

A
  • Similar to a TEM, uses a beam of electrons in a vaccum!
  • MAGNIFICATION: x200,00
  • RESOLUTION: 10nm
  • Image?&raquo_space; 3D images, black and white, with a DEAD specimen, with metallic stain
  • Computers normally add false colouring

metallic stains: may pose a toxic hazard to the users,

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9
Q

What is the structure of the smooth endoplasmic reticulum (SER)?

A

System of membranes with cisternae
No ribosomes

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10
Q

What is the function of the Smooth Endoplasmic Reticulum?

A
  • Contains enzymes to catalyse cellular reactions.
  • Undergoes lipid-synthesis and lipd transporation (within cell)
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11
Q

What is the structure of the Rough Endoplasmic Reticulum?

A
  • System of folded membranes, close to the nucleus, containing fluid-filled cavities called cisternae that are continuous with the nuclear membrane.
  • Coated with ribosomes
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12
Q

What is the function of the Rough Endoplasmic Reticulum?

A
  • Provides a large surface area for ribossomes (enhancing amino acid assembly)
  • Cisterae provides a channel to transport molecules in from nucleus.
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13
Q

What is the structure of the Nucleus?

A
  • A large organelle surrounded by a nuclear envelope, containing many nuclear pores, holding cell’s genetic information (DNA)

nuclear envelope = double membrane

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14
Q

What is the function of the Nucleus?

A
  • Controls the cell activities (controlling DNA Transcription)
  • Chromatin - DNA Complexfound in chromosomes
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15
Q

What is the structure of the Golgi Apparatus?
​

A
  • Collection of fluid fillled, membrane bound flattened sacs. Secretory vesicles can be pinched off to bring materials to and from (via edges)
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16
Q

What is the function of the Golgi Appuratus?

A
  • Carries out lipid-synthesis
  • Makes new lysosomes!
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17
Q

What is the structure of mitochondria?

A
  • Spherical, rod shaped or branched.
  • Surrounded by double membranes (inner and outer) with fluid filled space in between -> inner membrane folded into cristae
  • Fluid filled matrix
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18
Q

What is the function of the mitochondria?

A
  • Carries out aerobic respiration, where ATP is produced
  • Mostly found in energy intensive regions e.g muscle cells
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19
Q

What is the structure of Cilia/Undilipodia?

A
  • Small, hair like protrusions structures, made up of microtubles in a 9+2 formation structure
  • Such microtubles allow the cilia to MOVE SUBSTANCES!
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20
Q

What is the function of Cilia?

normall and epithelial!

A
  • Contains receptors that detects environmental changes for most cells
  • Epithelial Cilia - beating and moving bands of mucus in the trachea
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21
Q

What is the function of Undilipodia?

A

Only found in one place in animals: the sperm
Allows the sperm to move via tail like movements

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22
Q

What is the structure of Lysosome?

A

Small, single-membraned round bag-shapes with no interial structure

23
Q

What is the function of Lysosomes?

A
  • Containing digestive hydrolyctic enzymes to digest unused organelles and invading pathogens
  • Kept seperated from the cytoplasm

basically the cell’s dustbins…

24
Q

What is the Nucleolus’ function?

A
  • This will make ribossomes for RER for protiensynthesis, found in the nucleus
25
Q

What is the function of ribossomes?

A
  • Carries out proteinsynthesis, bound to the RER
26
Q

What is the structure of centrioles?

A
  • 2 bundles of microtubles perpendicular to one another, made of tubulin
27
Q

What is the function of centrioles?

A
  • Makes up the spindle fibres involved in cellular mitosis, formed perpendicular to each other
  • Makes up inner structure of cilia and undilipodia
28
Q

What is thefunction of chloroplast?

A
  • Carries out photosynthesis, where the grana (plural of granum) traps light energy
  • To produce glucose needed during plant respiriation (ATP)
29
Q

What is the function of cell vacuole?

A
  • This will provide cell stability and support, keeping cell rigid
  • Supports with cell water potential

has a membrance called: Tonoplast!

30
Q

What is the function of the cell wall?

A
  • This will provide cell stabilty and rigid strength.
31
Q

What are the features of an Optical Microscope?

give the mag, resolution, and uses

A
  • Uses visible light and lenses to magnify object images
  • RESOLUTION: 200nm
  • MAGNIFICATION: x1,500
  • Image&raquo_space; Uses white light, specimen may be living / dead
32
Q

State and explain the main different staining techniques

A
  • Differential Stain: More than one type of dye used, to highlight contrast between different organnelles
  • Simple Stain: One basic dye used to highlight contrast
33
Q

State and explain the 5 different stains

A

Methyl Blue : All purpose staining (animal, plant, blood ect)

Acectic Orcien: Binds and Stains DNA, in the chromosomes, in the nucleus - DARK RED*
Sudan Red: Binds and stains lipids - *RED**

  • Eosin Stain: Acidic Dye, staining cytoplasm - PINK
  • Iodine Stain - Staining Cellulose/Starch Granules - BLUE
34
Q

What are 4 main purposes of staining?

A
  1. To provide a higher contrast
  2. To allow internal structures to be more visible
  3. Some organelles to be more visible
  4. To allow a clearer image to occur
35
Q

State the 5 conventions of Low-Powered Drawings

A
  1. Smooth, continous lines without shading
  2. NO INDIVIDUAL CELLS, ONLY COMMON TISSUE
  3. Drawn to proportion always
  4. Lables HORIZONTAL to drawing
  5. Include Title, Mag and scale bars
36
Q

State the 5 conventions of High-Powered Drawings

A
  1. Smooth, continous lines without shading
  2. DRAW 15-20 LARGE INDIVIDUAL CELLS
  3. Drawn to proportion always
  4. Lables HORIZONTAL to drawing
  5. Include Title, Mag and scale bars

NOT EVEN SHADING FOR STAINS!!

37
Q

What is an eyepiece graticule? What is a stage micrometer?

A
  • Eyepiece graticule fitted into a microscope eyepiece, with 100 divisions and no scale = eyepiece units. It represents diff lengths at diff mags and so has to be calibrated for each objective lens.
  • A microscopic ruler is etched onto a slide = stage micrometer/stage graticule. each tiny unit is 10 micrometres, and the whole ruler is 1mm.
  • You line up the eyepiece graticule and stage micrometer as best as you can, see what equals what and then calculate what one eyepiece unit is worth
    in micrometres.
  • Measure how many eyepiece units the specimen is in width/length, and x by the micrometre amount.
38
Q

Define Transcription

A

The process of making mRNA from DNA strand

39
Q

Define Translation

A
  • Forming of protiens at ribossomes, through amino acid assembly with tRNA, always complamentary to the triplet codon, to mRNA.
40
Q

Decribe Division Of Labour (proteinsynthesis)

`

A
  1. In cell nucleus, DNA is unzipped by DNA Polymerase, removing double helix shape
  2. mRNA takes complementary base copy from DNA, leaves via nuclear pore, to RER > cisternae > ribossome
  3. Ribossomes read the BASE SEQUENCE in TRIPLETS
  4. tRNA is brought here, where assembled complemantary
  5. TRIPLET CODON FORMED: Where tRNA Molecules each have amino acids > peptide bonds > POLYPEPTIDE

mRNA = Coding Strand
DNA = Template Strand

41
Q

Decribe what happens to protiens after assembly in ribossomes!

A
  1. Transport VESICLE will transport the polypeptide chain to the Golgi Body
  2. At Body, this polypeptide will have its shape folded and modified, among others, into a SPECIFIED TERTAIRY STRUCTURE
  3. Secretory VESICLE will again transport modified molecule, FUSE WITH THE PLASMA MEMBRANE, and exits cell via EXOCYTOSIS!!!!
42
Q

Outline 4 of Cytoskeleton’s Main functions

give an example for each…

A
  • PROVIDES MECHANICAL STRENGTH - via mircotubles
  • AIDS TRANSPORTATION IN CELLS - vesicles, chomosome
  • ALLOWS CELL MOVEMENT - phagocytosis, endocytosis
  • ANCHORS ORGANELLES IN PLACE - nucleus in cytoplasm
43
Q

State the components of The Cytoskeleton!

A
  • Rod-Like Microfilaments
  • Cylindrical Microtubles
  • Intermidiate Filaments
  • Motor Protiens
44
Q

2 to mention

Structure and function of Microfilaments

Material and Diameter

A
  • Providing mechanical support, strength and shape
  • Allowing for cell movements via contractions e.g. Phagocytosis

7nm Diameter, made of Actin!

45
Q

2 to mention

Structre and function of Microtubles

Material and Diameter

A
  • Trackway for Motor Protiens, moving substances around cell
  • Spindle Fibres during Cell Division (chromosome movement)

20-30nm, made of Tubulin

46
Q

2 to mention

Structre and function of Intermidiate Filaments

Material and Diameter

A
  • Cell-Cell signalling system
  • Anchors the Nucleus in cytoplasm

10nm, made of many protiens

47
Q

Structre and function of Motor Protiens

Material…

A
  • Vesicle Transportation
  • Organelle Transportation
  • Chromosome movements

KINESIN AND DYNESIN!

48
Q

HOW TO PREPARE A LAB SLIDE IN 6 STEPS!

A
  1. Grossing - Trimming to appropiate size
  2. Tissue Fixations - Preserved in Formaldyhide + alcohol dehydtration
  3. Sectioning - Cutting down specimen ULTRA THIN
  4. Staining - Highlighting contrast of specimen
  5. Cover Slip - laid at an angle to prevent AIR BUBBLES, blocking view
49
Q

State 4 similarities of Prokaryotes and Eukaryotes

A
  • Both with ribossomes
  • Both with Cytoskeleton
  • Both with Cell wall
  • Both with Centrioles
50
Q

State the Cell wall materials of: Bacterium, Fungi and Plants

A
  1. Bacterium = Peptidoglycan
  2. Plant = Cellulose
  3. Fungi = Chitin
51
Q

State 7 differences of Prokaryotes and Eukaryotes

A
  • P: No membrane bound organelles of ANY SORT!! E: Contains these
  • P: Smaller cells, E: Larger Cells
  • P: 70s Ribossome, E: 80s Ribossome
  • P: No definite nucleus, E: Contains Defintie Nucleus
  • P: Has plasmids, E: No plasmids
  • P: Binary Fission, E: Mitosis (due to nucleus presence)
  • P: Simple cytoskeleton, E: Normal Cytoskeleton
52
Q

Give 4 main bacterial-only features

A
  • Mesosme: larger SA plane for chemical reactions in cytoplasm
  • Capsule: Slime Layering that protects virus infectoins and hides antigens (from immune attack)
  • Pili: Adheres to other cells and provides a medium of plasmid transfer
  • Flagellum: Tail to swim and move
53
Q

What 2 types of mounts can be done?

and explain ‘em..

A
  • Usually done for Optical Microscope
    Wet mount: adding a drop of water to the specimen before placiing coverslip- esp used for mobile organisms. Prevents distortion and flattens the sample.
  • Dry mount: no water, placing coverslip straight away - used for hairs, pollen etc.

OCR A-level Biology Module 2: Foundations in Biology (5 decks)

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