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Biology AS > Cells > Flashcards

Cells Flashcards

1
Q

Magnification

A

How much bigger the image is than the actual specimen

= size of image / size of real object

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2
Q

Resolution

A

How detailed the image is, how well the microscope distinguishes between two points that are close together

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3
Q

Light Microscope

A
  • Use light to form image
  • Resolution = 200nm
  • Magnify = X1,500
  • Can see mitochondria and nucleus but not in perfect detail
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4
Q

Transmission Electron Microscope (TEM)

A
  • Beam of electrons passes through thin specimen
  • Resolution = 1nm
  • Magnify = X1,500,000
  • Denser parts absorb more electrons and appear dark
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5
Q

Scanning Electron Microscope (SEM)

A
  • Beam of electrons passes across thick specimen and scatter
  • Resolution = 10nm
  • Magnify = X1,500,000
  • Scattering pattern builds up 3D image based on contours of specimen
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6
Q

Electron Microscope Limitations

A
  • Whole system must be in a vacuum
  • Specimen must be thin for TEM electrons to pass through
  • Complex staining process is needed, might introduce artefacts to image
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7
Q

Optical Microscopes

A
  • Drop of water on slide using pipette
  • Thin specimen on top with tweezers
  • Drop of stain (highlight objects in cell)
  • Cover slip
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8
Q

Separating Cell Components

A
  • Cell fractionation
  • Homogenation (then into ice-cold, buffered, isotonic solution)
  • Filtration (separate large cell debris)
  • Ultracentrifugation (dense pellet at bottom, supernatant at top)
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9
Q

Cell Surface Membrane

A
  • Made up of lipids and proteins

- Regulates movement of substances into and out of the cell

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10
Q

Nucleus

A
  • Large organelle surrounded by a nuclear envelope and has pores
  • Controls cell activity and contains DNA
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11
Q

Mitochondria

A
  • has a double membrane with inside one folding to form cristae
  • Contains enzymes involved in respiration and is the site where ATP is produced
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12
Q

Chloroplast

A
  • Flat structure with double membrane

- Site for chemical reactions

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13
Q

Golgi Apparatus

A
  • Group of fluid filled flattened sacs
  • Package and process new lipids and proteins
  • Makes vesicles
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14
Q

Golgi Vesicle

A
  • Vesicle produced by Golgi Apparatus

- Stores lipids and proteins and transports them out of the cell

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15
Q

Lysosome

A
  • A vesicle containing digestive enzymes called lysozymes (used in invading cells)
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16
Q

Ribosomes

A
  • Site where proteins are made
  • 80s ribosomes found in eukaryotic cells
  • 70s found in prokaryotic cells
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17
Q

Rough Endoplasmic Reticulum (RER)

A
  • Covered with ribosomes

- Folds and processes proteins that have been made at the ribosomes

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18
Q

Smooth Endoplasmic Reticulum (SER)

A
  • No ribosomes

- Synthesizes and processes lipids

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19
Q

Cell Wall

A
  • Rigid structure
  • Made of cellulose in eukaryotic cells
  • Made of murein in prokaryotic cells
  • Supports the shape of cells, gives them turgid structure
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20
Q

Cell Vacuole

A
  • Membrane bound organelle in cytoplasm
  • Contains cell sap
  • Helps maintain pressure inside the cell to keep it rigid
21
Q

Plasmids

A
  • Circular piece of DNA

- Found in prokaryotic cells and viruses

22
Q

Flagellum

A
  • A tail like structure which rotates to move the cell

- Found in prokaryotic cells and viruses

23
Q

Circular DNA

A
  • Floats free in the cytoplasm
  • One long coiled up strand
  • Found in prokaryotic cells and viruses
24
Q

Capsule

A
  • Protective slimy layer
  • Helps cell retain moisture and adhere to surfaces
  • Found in prokaryotic cells and viruses
25
Q

Prokaryotic Cell Replication

A
  • Binary Fission
  • Circular DNA and plasmids replicate
  • Cell gets bigger
  • DNA loops and plasmids move to opposite ends
  • Cytoplasm divides creating two daughter cells
26
Q

Viruses

A
  • Acellular (nucleic acids surrounded by protein)
  • Core of genetic material (DNA or RNA)
  • Capsid (protein coat around the core)
  • Attachment proteins (stick out of capsid, bind to complementary antigens on host cells surface)
27
Q

Interphase [Mitosis]

A
  • Cell carries out normal functions

- DNA and organelles replicate at the end

28
Q

Prophase [Mitosis]

A
  • Chromosomes condense
  • Centrioles move to opposite end of the cells
  • Forming spindle fibres which help pull chromosomes
  • Nuclear envelope breaks down
  • Chromosomes lie free in cytoplasm
29
Q

Metaphase [Mitosis]

A
  • Chromosomes line up in the middle of the cell

- Their centromeres attach to spindle fibres

30
Q

Anaphase [Mitosis]

A
  • Centromeres divide
  • Separating each pair of sister chromatids
  • Spindles contract and pull chromatids to opposite poles
31
Q

Telophase [Mitosis]

A
  • Chromatids reach opposite poles
  • They uncoil and become long and thin again
  • A nuclear envelope forms around groups of chromosomes
  • Making two new nuclei
32
Q

Cytokinesis [Mitosis]

A
  • The cytoplasm divides

- Leaving two new genetically identical daughter cells

33
Q

Cancer Cells

A
  • Incontrollable dividing of cells

- Caused by a growth disorder of cells

34
Q

Benign Tumor

A
  • More treatable as it stays in one place
  • Has less rapid division
  • Is compact so it’s easier to remove
35
Q

Malignant Tumor

A
  • Less treatable
  • As it spreads through the lymphatic system
  • Through lymph nodes this spreads the tumor cells
36
Q

Cancer Treatments

A
  • Chemotherapy uses chemicals
  • Prevent DNA replication by inhibiting metaphase (prevent spindle formation)
  • Drugs are taken up by cancer cells most as they respire most
37
Q

Fluid Mosaic Structure

A
  • The phospholipid bilayer is fluid as it moves constantly

- Cholesterol and proteins present are scattered randomly like mosaic tiles

38
Q

Components Of The Membrane

A
  • Phospholipids (hydrophilic heads and hydrophobic tails)
  • Cholesterol (restrict phospholipid movement, add rigidity and maintain shape)
  • Proteins (channel and carrier help large molecules and ions pass through)
  • Glycolipids (polysaccharide chain attached, maintain stability, help cells attach to form tissues)
  • Glycoproteins (polysaccharide chain attached, act as surface receptors, detect chemicals released from other cells)
39
Q

Permeability

A
  • How easy it is for substances to move across a membrane
  • Temperature: hydrogen bonds broken by kinetic energy increase permeability
  • Ethanol: solvent dissolves fats and increases permeability
  • pH: interferes with H- and OH+ bonding increasing permeability
40
Q

Diffusion

A
  • The net movement of molecules
  • From a region of high concentration to one of lower concentration
  • Passive process (no energy)
41
Q

Fick’s Law

A

= SA X CD / diffusion pathway

  • Greater surface area, faster rate of diffusion
  • Shorter length of diffusion, faster rate of diffusion
  • Greater the concentration difference, faster rate of diffusion until equilibrium is reached
42
Q

Carrier Proteins

A
  • Move large molecules across membrane down their concentration gradient
  • Molecule attaches to protein changing it’s shape
  • Then its released on the opposite side of the membrane
  • Facilitated Diffusion
43
Q

Channel Proteins

A
  • Form pores in the membrane

- For charged particles (ions) to diffuse through down their concentration gradient

44
Q

Osmosis

A
  • Movement of water
  • Across a partially permeable membrane
  • From a region of high water potential to a region of low water potential
45
Q

Types Of Solutions [Osmosis]

A
  • Hypertonic: low water potential, water moves out of cell into solution, animal cell shrinks and plasmolysis occurs
  • Hypotonic: high water potential, water moves into cell, animal cells expand, plant cell goes turgid
  • Isotonic: same water potential as the cell, water moves in and out at the same rate, no damage to cell
46
Q

Active Transport

A
  • Movement of substances
  • Against a concentration gradient
  • From a region of lower concentration to a region of high concentration
  • Active process (requires energy in from of ATP)
47
Q

Active Transport Process

A
  • Carrier proteins bind their receptor sites to molecule/ion
  • In the cell, ATP binds to protein (hydrolysis reaction)
  • Protein changes shape, opens on opposite side of the membrane
  • Releases the molecule/ion
  • Phosphate molecule is released and protein reverts to original shape
  • Phosphate returns to bind to ADP to form ATP during respiration
48
Q

Co-Transport

A
  • Type of carrier protein
  • Bind two molecules at a time
  • Uses concentration gradient of one molecule to move the other against it’s own concentration gradient
49
Q

Glucose [Transport Example]

A
  • Sodium ions actively transported from ileum epithelial cells to blood
  • Via sodium-potassium pumps
  • Creates concentration gradient (more sodium ions in lumen of ileum than epithelial cells)
  • Sodium ions diffuse from lumen into epithelial cells down their concentration gradient
  • Via a co-transporter carrying glucose against it’s concentration gradient
  • Glucose diffuses out of the cell into the blood down it’s concentration gradient
  • Via a protein channel by facilitated diffusion

Biology AS (7 decks)

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