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Biology > Cells Part 2 ( Cell Cycle, Mitosis, Trasnport Across Cell Membrane) > Flashcards

Cells Part 2 ( Cell Cycle, Mitosis, Trasnport Across Cell Membrane) Flashcards

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1
Q

Describe Binary fission

A

Replication of circular dna - cell gets bigger, both copies starch to cell membrane
Replication of plasmids
Cell membrane grows and begin to pinch inwards
Division of cytoplasm to produce daughter cells

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2
Q

What does the cell cycle consist of

A

Interphase, mitosis, cytokines

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3
Q

What happens during interphase

A

Cell growth and replication
Chromosomes replicated - chromatids
Chromatin- chromosome - chromatids

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4
Q

What is prophase

A

Nuclear membrane and nucleolus break down
Chromosome condense
Centrosomes move to opposite ends of nucleus where they form poles

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5
Q

What is metaphase

A

Centromeres attach to spindle fibres
Chromosomes/ pairs of chromatids line up at the equator of the spindle/ cell- attached by their centromeres
No nuclear envelope

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6
Q

What is anaphase

A

Centromeres divide
Chromatids pulle dot opposite poles/ end sof cell
Spindle fibres shorten

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7
Q

What is telophase and cytokinesis

A

Sister chromatids reach opposite sides and decondense
Nuclear membrane and nucleoli reform

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8
Q

What is a telomere

A

Repetitive dna sequences at the end of a chromosome
Protects the end of chromosome from being frayed/ tangled

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9
Q

What is metastasis

A

Spreading of malignant/ cancerous tumour
By apricots eof tumour breaking off and travelling in blood/lymph
Forms a secondary tumour
Greatly reduced survival chances

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10
Q

Describe and explain what a student should to when counting cells to make sure the mitotix index was o accurate

A
  1. Examine large number of felds of view i many cells:
    Mark as pairs only
    Accept large number / 20 or more for many
  2. To ensure representative sample;
    Accept typical / reliable
    OR
  3. Repeat count;
    4.To ensure figures are correct;

OR
5. Method to deal with part cells shown at edge /count only whole cells;
6. To standardise counting:

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11
Q

What is the purpose of of the cell-surface membrane

A

Boundary between cytoplasm and the environment
Border and allows cells to interact with their environment in a controlled way
Moves substance sin and out of cell

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12
Q

What is the function of the phospholipid bilayer

A

Allow lipid soluble, prevent water soluble
Make membrane flexible
Small, non-polar, lipid soluble

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13
Q

Describe how the phospholipid bilayer forms

A

Fatty acid/ hydrophobic tails pointing in each other
Phosphate/ polar/ hydrophilic heat pointing out - insert city water

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14
Q

When does the fluidity of the membrane increase

A

Temp and number of double bonds increase
Decrease cholesterol

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15
Q

Why is it called a fluid mosaic model

A

Phospholipids cna move relative to each other
Proteins vary in size

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16
Q

What are extrinsic proteins

A

On the surface/ partly embedded
Mechanical support
Act as receptors

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17
Q

What are intrinsic proteins

A

Completely span the membrane

18
Q

What are the functions of proteins in a cell membrane

A

Provide support
Carry wat ersoluble ubstances
Allows active transport
Form recognition sites
Help cells adhere together
Act as receptors

19
Q

What is the function of cholesterol in a cell -membrane

A

Reduce lateral movement for meolciles
Make membrane less fluid at higher temperatures
Prevent leakage eof water and dissolved ions

20
Q

What are the functions of glycolipids

A

Act as recognition sites
Maintain stability of the membrane
Help cells attach to one another and so form tissues

21
Q

What are the functions of glycoproteins

A

Recognition sites
Helps cells attach to one another and form tissues

22
Q

What is Exocytosis

A

Secrets substance outside of cell by releasing them from a vesicle
Fuse with plasma membrane

23
Q

What is endocytosis

A

Cells takes ins substance by invagination a portion of the plasma membrane and forming vesicle around the substance

24
Q

What is pinocytosis

A

Absorbing dissolving material
Cell gulps droplets of fluid by forming tiny vesicles

25
Q

What is diffusion

A

The movement of particles from a region of high concentration to an area of low concentration (down a concentration gradient) until evenly spread. The particles that pass through must be small, lipid soluble, and uncharged. It is a passive process that requires no input of energy in the form of ATP

26
Q

What factors does diffusion depend on

A

It depends upon;

  • the membranes composition
  • Number of pores
  • Size of diffusing molecules
  • Whether its lipid soluble
  • Whether its polar

Concentration gradient
Temperature
Sa
Diffusion difference

27
Q

What is facilitated diffusion

A

the movement of particles down as concentration gradient using channel or carrier proteins. This is when the diffusion is evenly spread up by specific proteins in the cell membrane, however it can be limited by the number of proteins. Only energy used is kinetic energy that the molecule already has, its a passive processes. Occurs at channels on the membrane where there are special carrier molecules

It occurs down the concentration gradient and doesn’t require energy. It transports substances, such as glucose, that aren’t lipid soluble

28
Q

What are carrier proteins

A

Take substances from one side to another

29
Q

What are channel proteins

A

Protein pores that open and close

30
Q

What is osmosis

A

Osmosis is the movement of water molecules from a solution with a higher water potential to a solution with a lower water potential through a partially permeable membrane

31
Q

What is water potential

A

Water potential, psi, is a measure of how easy it is for water to move. The more water molecules there are present the more easily they can move so the higher the water potential. Water potential is measured in units of pressure, usually kilopascals

Distilled water has a greatest number of water molecules in a given volume as it is pure water- we say it has the water potential has 0. All other solutions will have a value less than 0- they will always be negative

32
Q

What protein channels do water move through

A

Aquaporin

33
Q

What is hypotonic

A

Higher water potential
Water enter cells- burts and swells
Plant cells- turgid (cell wall)

34
Q

What isotonic

A

Equal water potential so water neither enters nor leaves

35
Q

What is hypertonic

A

Lower water potential
Water leaves cell
Shrinks
Plants- plasmolysised

36
Q

What is active transport and describe the process

A

Active transport is the movement of molecules or ions into or out of the cell from a region of lower concentration to a region of higher concentration using ATP and carrier proteins

  1. Molecule or ion being transported binds to receptor sites on the carrier protein
  2. On the inside ATP binds to the carrier protein and splits into ADP and a phosphate molecule
  3. The carrier protein changes shape and opens up on the opposite side, releasing the molecule/ion to the other side of the molecule
  4. The phosphate molecule is released from the carrier protein, causing it to revert back to its original shape. ADP + Pi recombine during respiration to form ATP
37
Q

What is cotransport

A

2 different substances involving carrier proteins

Uses atp
Sodium ion and proton bind to protein
Protein changes shape to move sodium ion and proton across cell membrane

  1. Sodium ions actively transported from ileum
    cell to blood;
  2. Maintains / forms diffusion gradient for sodium
    to enter cells from gut (and with it, glucose);
  3. Glucose enters by facilitated diffusion with
    sodium ions;
38
Q

Factors affecting the rate of absorption

A
  1. The concentration of glucose
  2. Temperature
  3. Amount of protein channels/ carriers
  4. Amount of co-transport proteins
39
Q

Explain how a tissue loses mass

A

1.Water potential of solution is less than / more negative than that of potato
tissue; Allow Ψ as equivalent to water potential
2. Tissue loses water by osmosis

40
Q

Why do membranes of white blood cells have less cholesterol

A

Membrane less rigid and more fluid
Fit through openings in capillaries
Attracted by chemicals for immune response - chemotaxis

41
Q

What does histamine do

A

Dilates blood vessels
Increases permeability of capillary wall

Biology (13 decks)

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