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Biology Paper 1 > Cells > Flashcards

Cells Flashcards

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1
Q

Magnification equation

A

Magnification = image size / real object size

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2
Q

What is resolution?

A
  • Minimum distance apart that two objects can be distinguished as separate objects in an image.
  • The greater the resolution the more clear the image will be
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3
Q

Properties of optical microscopes

A
  • Use light
  • Cannot see small internal organelles eg, ribosomes
  • Low resolution and magnification
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4
Q

Properties of SEM (scanning electron microscope)

A
  • Can use thick specimen
  • Lower resolution than TEM
  • 3D image
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5
Q

Properties of TEM (transmission electron microscope)

A
  • High resolution, so you can see internal organelles
  • Only used on thin specimens
  • No living specimens
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6
Q

Why should a solution be kept ice cold?

A

To reduce enzyme activity that breaks up organelles

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7
Q

Why should the solution be isotonic?

A

To prevent the osmotic pressure of the cell changing and destroying the organelles

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8
Q

Why is a buffer solution used?

A

To maintain the pH

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9
Q

What do eukaryotic cells have?

A

A nucleus and membrane bound organelles

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10
Q

Function of the nucleus

A
  • Controls the cell’s activity
  • The nuclear pores allow substances to pass in and out of the nucleus
  • The nucleolus makes ribosomes
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11
Q

Function of RER (rough endoplasmic reticulum)

A
  • Folds and processes proteins
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12
Q

Function of SER (smooth endoplasmic reticulum)

A
  • Synthesises and processes lipids
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13
Q

Function of Golgi apparatus

A
  • Processes and packages new lipids and proteins

- Also makes lysosomes

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14
Q

Function of Golgi vesicles

A
  • Stores lipids and proteins

- Transports it out of the cell

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15
Q

Function of Mitochondria

A
  • Site of aerobic respiration where ATP is produced
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16
Q

Function of Ribosomes

A
  • Site where proteins are made
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17
Q

Function of lysosomes

A
  • Contain lysozymes which are digestive enzymes
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18
Q

Function of cell membrane

A
  • Regulates the movement of substances in and out the cell

- Also has receptor molecules

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19
Q

Function of the cell wall

A
  • Supports cell
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20
Q

Function of chloroplasts

A
  • Site where photosynthesis takes place
21
Q

Function of cell vacuole

A
  • Helps maintain pressure and keep cell rigid

- Involved in isolation of unwanted chemicals

22
Q

Function of capsule

A
  • Protect bacteria from attacks from the cells of the immune system
23
Q

What are viruses?

A
  • Non living structures which contain nucleic acid enclosed in a capsid
24
Q

The role of mitosis?

A

To produce identical daughter cells for growth and asexual reproduction

25
Q

Stages of cell cycle

A
  • Mitosis
  • Interphase
  • Cytokinesis
26
Q

What is mitosis?

A
  • A form of cell division that produces identical cells,

- There are four stages of mitosis: prophase, metaphase, anaphase and telophase

27
Q

What happens in interphase?

A
  • The cell grows & then prepares to divide
  • Chromosomes & some organelles are replicated
  • Chromosomes also begin to condense
28
Q

What happens in cytokinesis?

A
  • The parent & replicated organelles move to opposite sides of the cell
  • The cytoplasm divides thus producing two daughter cells
29
Q

Why is mitosis important?

A
  • Growth: all cells produced are identical so organisms can grow using mitosis.
  • Repair: all cells produced are identical so organisms can replace dead tissues using mitosis.
  • Reproduction: some single-celled organisms, like yeast, reproduce by dividing into two identical daughter cells by mitosis.
30
Q

What occurs in prophase?

A
  • Chromosomes condense
  • Centrioles move to opposite ends of the cell forming spindles
  • Nuclear envelope breaks down
31
Q

What occurs in metaphase?

A
  • Chromosomes line up along the middle of the cell

- They become attached to the spindle by the centromeres

32
Q

What occurs in anaphase?

A
  • Centromeres divide, separating each pair of sister chromatids
  • Spindles contract, pulling chromatids to opposite poles of the spindle
33
Q

What occurs in telophase?

A
  • Chromatids reach the opposite ends on the spindle
  • They uncoil and become chromosomes
  • Nuclear envelope forms around each group of chromosomes creating 2 nuclei
  • Cytokinesis finishes leaving two genetically identical daughter cells
34
Q

Steps of Required Practical 2- Mount slide

A
  • Cut 2 cm tip of the root and place in HCl for about 15 minutes
  • Rinse the tip with distilled water
  • Cut off 1 mm of the tip and place on a slide
  • Cover the sample with toluidene blue and macerate with amounted needle
  • Add cover slip and squash the material gently and place under a microscope
  • Calculate the mitotic index
35
Q

How to calculate the mitotic index

A

Number of cells undergoing mitosis / total number of cells observed

36
Q

How do you calculate the size of cells?

A
  • Using a eyepiece graticule

- Or the IAM equation

37
Q

What happens in G1?

A
  • Cell growth and protein production
38
Q

What happens in the S phase?

A

DNA replication

39
Q

What is binary fission?

A
  • The process at which prokaryotic cells divide
40
Q

The stages of binary fission

A
  • The circular DNA in the cells replicates & both copies attach to the cell membrane. Plasmids replicate.
  • The cell membrane begins to grow between the two DNA molecules & begins to pinch inwards, dividing the cytoplasm in two.
  • A new cell wall forms between the two DNA molecules dividing the original cell.
41
Q

What is a cell membrane made up of?

A
  • Phospholipids with proteins in between

- Also contains receptors

42
Q

Why are cell membranes described as fluid mosaic?

A
  • The phospholipids are constantly moving

- The proteins are scattered

43
Q

The role of cholesterol

A
  • Make the membrane more rigid and reduce the lateral movement of the phospholipids.
  • It also prevents the leakage of water and dissolved ions from the cell as it is very hydrophobic.
44
Q

The role of glycolipids

A
  • Acts as cell surface receptors for certain molecules.

- They also allow cells to adhere(stick) to one another to form tissues

45
Q

The role of glycoproteins

A
  • Acts as cell surface receptors and neurotransmitters.

- These allow cells to recognise one another as well as attach to form tissues

46
Q

What is diffusion?

A
  • Passive movement of small, non-polar, lipid soluble molecules such as carbon dioxide and oxygen from an area of high concentration to an area of low concentration
47
Q

What is osmosis?

A
  • Diffusion of water molecules from an area of high water potential to an area to low water potential through a partially permeable membrane
48
Q

Active transport

A
  • Can transport all types of molecules through carrier proteins from an area of low concentration to an area of high concentration.
  • However, this process requires energy in the form of ATP
49
Q

Factors that increase the rate of diffusion

A
  • Large surface area
  • Short diffusion pathway
  • Steep diffusion gradient
  • An increase in temperature

Biology Paper 1 (7 decks)

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