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Biology > Topic 2A: Cell Structure and Division > Flashcards

Topic 2A: Cell Structure and Division Flashcards

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1
Q

Cell membrane

A
  • Regulates movement of substances in and out of the cell
  • Have receptors to respond to chemicals e.g. hormones
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2
Q

Nucleus

A
  • Nuclear envelope = double membrane with pores
  • Holds chromosomes –> protein bound DNA
  • Controls cell activity
  • Nucleolus - makes ribosomes
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3
Q

Mitochondria

A
  • Double membrane –> inner folded to make cristae
  • Matrix = inside the membranes = has enzymes for respiration
  • Does aerobic respiration for ATP
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4
Q

Chloroplast

A
  • Double membrane
  • Thylakoid membranes inside –> stack to make grana –> linked by lamellae (thin, flat pieces of thylakoid)
  • Does photosynthesis –> some in grana, some in stroma
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5
Q

Golgi apparatus

A
  • Fluid filled, membrane bound, flattened sacs
  • Process and package lipids and proteins
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6
Q

Vesicles

A
  • Smaller sacs around Golgi
  • Stores lipids and proteins and transports them out of the cell
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7
Q

Lysosome

A
  • Type of Golgi vesicle
  • Has lysozymes that digest invading cells or worn out cell parts
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8
Q

Ribosome

A
  • Float free or on RER
  • Made of proteins and RNA
  • Does protein synthesis
  • Not surrounded by a membrane
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9
Q

Rough Endoplasmic Reticulum

A
  • System of membranes covered in ribosomes
  • Folds and processes proteins made by ribosomes
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10
Q

Smooth Endoplasmic Reticulum

A
  • No ribosomes
  • Synthesises and processes lipids
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11
Q

Cell wall

A
  • Cellulose in plants
  • Chitin in fungi
  • Supports cell and stops it changing shape
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12
Q

Vacuole

A
  • Contains cell sap –> sugar and salt solution
  • In membrane - tonoplast
  • Maintains pressure in plant cells
  • Isolates unwanted chemicals
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13
Q

What are prokaryotic cell walls made of?

A

Murein

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14
Q

Slime capsule

A
  • Protects them from attack by the immune system
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15
Q

Plasmid

A
  • Small DNA loops containing specific genes
  • Can be passed between cells
  • Not always present
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16
Q

Circular DNA

A
  • No nucleus –> DNA floats free
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17
Q

Cytoplasm

A
  • Holds no membrane bound organelles
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18
Q

Ribosomes in prokaryotes

A
  • Much smaller than in eukaryotes
19
Q

Flagella

A
  • Long hair-like structure
  • Rotates to allow the cell to move
20
Q

Describe the process of binary fission

A
  • Circular DNA and plasmids replicate –> circular only once, plasmids can replicate multiple times
  • Cell grows –> DNA loops move to opposite ends
  • Cytoplasm begins to divide + new cell walls begin to form
  • Cytoplasm divides and 2 daughter cells produced –> each has one circular DNA and a variable number of plasmids
21
Q

How are viruses structured?

A
  • Core of genetic info (DNA / RNA)
  • In a protein coat (capsid)
  • Attachment proteins –> allow virus to attach to a host cell
22
Q

Describe virus replication

A
  • Virus attach attachment proteins to complimentary receptor proteins on the host cell surface –> some viruses can only infect one type of cell
  • They inject the host cell with their DNA / RNA and use its own parts to reproduce
23
Q

Define magnification

A

How much bigger an image is than the specimen

24
Q

Define resolution

A

How detailed an image is –> how easy it is to distinguish between two points

25
Q

What is the equation for magnification?

A

Magnification = image size / actual size

26
Q

Light microscopes

A
  • Use light to form an image
  • Max resolution = 0.2 micrometres –> can see nucleus
  • Max mag = x1500
  • Can view live specimens
  • Can see in colour
27
Q

Electron microscopes

A
  • Use electrons to form an image
  • Higher resolution –> 0.0002 micrometres
  • Max mag = 1,500,000
  • Black and white images only
  • Specimens must be dead
28
Q

Transmission Electron Microscopes

A
  • Transmit a beam of electrons through the sample
  • Denser parts absorb more –> look darker
  • Has high resolution –> can see internal structure of organelles
  • Can only be used on thin specimens
29
Q

Scanning Electron Microscopes

A
  • Scan a beam of electrons over specimen knocking off electrons from the specimen –> collected in cathode ray tube to make the image
  • 3D image
  • Can be used on thicker specimens
  • Lower resolution
30
Q

What are microscope artefacts?

A
  • Things you can see down a microscope that are not parts of the cell e.g. fingerprints, bubbles, dust
31
Q

Describe homogenisation and conditions needed

A
  • Vibrate or grind cells to break membrane and release organelles
  • Ice cold –> reduces enzyme activity to stop organelles being broken down
  • Isotonic –> same conc in and out to prevent damage to organelles by osmosis
  • Buffer solution –> maintains pH
32
Q

Desrcibe filtration of cell components

A
  • Filtered through a gauze to remove large cell / tissue debris
33
Q

Describe ultracentrifugation

A
  • Cell fragments in solution spun in centrifuge
  • Heaviest organelles flung to the bottom = pellet
  • Suspended organelles = supernatant
  • Supernatant drained off + spun again
  • Repeated to separate all organelles
  • Nuclei, chloroplasts (if present), mitochondria, lysosomes, RER + SER, ribosomes
34
Q

Describe interphase

A
  • G1= cell grows and new proteins and organelles are made
  • S = DNA replicates
  • G2 = cell keeps growing + proteins needed for mitosis are made
35
Q

What is mitosis used for?

A

Growth and repair

36
Q

Describe the stages of mitosis

A
  • Prophase –> chromosomes condense, centrioles move to opposite ends and form spindles, nuclear envelope breaks down
  • Metaphase –> Chromosomes line up down the middle + spindles attach to centromere
  • Anaphase –> Centromeres divide and sister chromatids separate, spindles contract pulling chromatids to opposite ends
  • Telophase –> Sets of chromosomes collect at opposite ends, new nuclear membranes form, chromosomes become long and thin again, cytoplasm divides
37
Q

What is cancer?

A
  • Uncontrolled cell growth due to a gene mutation
  • Cell division stops responding to normal regulations so cells rapidly divide
  • Cells clump to form tumours
38
Q

What are benign tumours?

A
  • Divide at a normal rate, don’t invade other tissues
  • Usually harmless but can press on other organs and impact their function
  • If needed they can be surgically removed
39
Q

What are malignant tumours?

A
  • Divide rapidly and interfere with organ functions
  • Invade other tissues via metastasis
  • Parts can break off and travel round the body to form secondary growths making it very harmful and difficult to treat
40
Q

What are come causes of cancer?

A
  • Genetics e.g. BRCA1+2
  • Radiation exposure –> including UV
  • Substances e.g. smoking, alcohol
41
Q

What are some treatments for cancer?

A
  • Chemotherapy –> prevents synthesis of enzymes needed in DNA replication to stop the cell cycle –> usually drugs that target quick dividing cells
  • Radiotherapy –> can damage DNA so it doesn’t make it past checkpoints preventing cell cycle
  • Surgery
  • Drugs –> can prevent spindle fibres forming to prevent mitosis
42
Q

Describe the root tip squash practical.

A
  • Cut 1cm tip off the root
  • Put HCl in a test tube in a water bath at 60 degrees
  • Put the tip in the acid and leave for 5 mins
  • Pipette rinse the tip with water and dry
  • Cut 2mm of the tip off and put on a microscope slide
  • Use a mounted needle to break the tip open and spread the cells thinly
  • Add a stain to make the chromosomes easier to see
  • Place a cover slip over and push down on top to squash the tissue
  • Observe with a microscope
43
Q

What is the calculation for mitotic index?

A

mitotic index = number of cells with visible chromosomes / total number of cells observed

Biology (16 decks)

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