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Biology > Cells > Flashcards

Cells Flashcards

1
Q

What is a eukaryotic cell?

A

A cell with a distinct nucleus and membrane bound organelles

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2
Q

What is a eukaryote?

A

A whole organism made of eukaryotic cells.

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3
Q

What is the function of a nucleus?

A

Managing the cell’s genetic material.

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4
Q

What is the function of the mitochondrion?

A

Produce energy through cellular respiration.

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5
Q

What is the function of ribosomes?

A

Protein-synthesis.

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6
Q

What is the structure of a nucleus?

A

Nuclear envelope, double membrane, helps control what goes in/out of the nucleus.
Nucleoplasm
Nucleolus, where ribosomes are made
Chromosomes, coils round proteins called histone proteins which are together called chromatin.
Nuclear pores, allow things like RNA to leave the nucleus

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7
Q

What is the structure of the mitochondrion?

A

Matrix, enzymes and proteins needed for respiration
Double membrane, controls what goes into and out of the mitochondria
Cristae, fold around and create the matrix, increases more surface area for enzymes involved in ATP.

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8
Q

What is the function of the chloroplasts?

A

Synthesise food by the process of photosynthesis

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9
Q

What is the structure of the chloroplasts?

A

Surrounded by a double membrane which contains thylakoids, folded membrane embedded with pigments
Fluid filled stroma contains enzymes for photosynthesis
Found in plants
Grana, where the first stage of photosynthesis takes place
Lamelle, connects the grana together

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10
Q

What is the function of the Golgi apparatus?

A

Helps process and package proteins and lipid molecules
Forms glycoproteins and lysosomes

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11
Q

What is the structure of the Golgi apparatus?

A

Fluid filled membrane sacs
Small rounded hollow vesicles

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12
Q

What is the function of the lysosomes?

A

Digests invading cells and breaks down worn out parts of cells

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13
Q

What is the structure of the lysosomes?

A

Contains hydrolytic enzymes
Enzymes surrounded by membrane

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14
Q

What is the structure of ribosomes?

A

Loose in cytoplasm or attached to rough endoplasmic reticulum
Made of protein and RNA
80s ribosomes, slightly bigger than prokaryotic
Very small

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15
Q

What is the function of the rough endoplasmic reticulum?

A

Folds and packages proteins and sends them to Golgi apparatus
Provides a pathway for the transport of proteins throughout the cell

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16
Q

What is the structure of the rough endoplasmic reticulum?

A

Has ribosomes on the outer surface of membranes
Sheet like membranes

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17
Q

What is the function of the smooth endoplasmic reticulum?

A

To synthesise, store and transport lipids and carbohydrates
Packages molecules and sends them to the Golgi apparatus

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18
Q

What is the structure of the smooth endoplasmic reticulum?

A

Does not have ribosomes

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19
Q

What is the function of the cell wall?

A

Supports the cell, provides strength and prevents lysis/ change of shape

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20
Q

What is the structure of the cell wall?

A

Made out of cellulose in plant and algal cells
Made out of chitin in fungi
Consists of a number of polysaccharides

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21
Q

What is the function of the cell vacuole?

A

Store nutrients and water on which a call can rely for its survival
Isolates unwanted chemicals inside the vell
Maintains pressure inside the cell

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22
Q

What is the structure of the cell vacuole?

A

Contains cell sap, weak solution of sugar and salts
Surrounding membrane called tonoplast

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23
Q

What is the structure of the bacterial cell?

A

Cell membrane
Circular DNA
Cell wall- made out of murein, strengthen and support, prevent osmotic lysis
Plasmids- genes for antibiotic resistance
Cytoplasm
Capsule- mucilaginous slime layer
Flagellum
Ribosomes
Some chlorophyll associated with cell membrane

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24
Q

What is the structure of a virus?

A

Attachment proteins, identify and bind to suitable host cells.
Capsule, protein
Genetic material (RNA) , nucleic acid
Lipid envelope, some but not all
Acellular
Non-living, can’t reproduce by themselves, need a host cell
20-300nm, smaller than prokaryotic cells

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25
Q

What is the formula for magnification?

A

Image size/ actual size

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26
Q

What is the formula for image size?

A

Actual size x magnification

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27
Q

What is the formula for actual size?

A

Image size/ magnification

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28
Q

Millimetre to micrometer?

A

X 1000

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29
Q

Micrometer to nanometer?

A

X 1000

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30
Q

Properties of light microscopes?
Magnification?
Resolution?

A

-light forms an image
-lenses magnify the image
-without light, no magnification
-max resolution = 0.2 micrometers
-cannot see objects smaller than 0.2 micrometers ( ribosomes, lysosomes)
- anything closer than 0.2 micrometers will be seen as the same object
- max magnification= X 1500
- can see specimen in colour
-can be used to see living specimen

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31
Q

Two types of electron microscopes?

A

Transmission electron microscopes
Scanning electron microscopes

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32
Q

Properties of transmission electron microscopes?
TEMs

A

-electrons form an image
-electromagnets focuses a beam of electrons from underneath the sample
-beam of electrons form underneath specimen, electromagnets ensure focus
-denser the specimen= more electrons absorbed= denser on image
- resolution= 0.1nm max
- max magnification = X1 500 000
-photomicrograph, picture or image can be formed
-beams of electrons, not light so no colour
- complex preparation to form slides, staining, thin, need to be in a vacuum
-needs vacuum otherwise particles in air affect beam of electrons
-harder to look at live organisms, specimen needs to be dead
-cannot build an ideal image with thin specimen, too thick- blacked out image
-artefacts possible

33
Q

Properties of scanning electron microscope?

A

-electrons from above passed back and forth
-electrons scatter, 3D image can be built
-resolution 20nm
-specimen doesn’t need to be as thin, electrons aren’t being absorbed
- vacuum
-artefacts

34
Q

How do scientists determine artefacts?

A

-use many preparation techniques to check if it always shows on the image.
-prepare many slides of the same thing
-if something is missing, artefact

35
Q

How to prepare a temporary mount?

A
  1. Water drop on slide using pipette
  2. Specimen placed onto slide with water droplet using tweezers
  3. stain places on specimen using a pipette
  4. cover slip slowly placed onto stained specimen using a mounted needle
36
Q

Process of homogensiation?

A

-The cells are grounded in homogeniser to break open the plasma membrane and release the organelles into the homogenate
-Solution (homogenate) must be:
Ice cold- prevent enzyme activity
Buffered- prevent enzymes from denaturing
Isotonic- same water potential as cells/ organelles
-cells are then filtered to remove whole cells and debris that had not broken up

37
Q

Process of cell fractionation?

A

-test tubes containing the homogenate are spun in a centrifuge on a slow speed
-heaviest organelles like the nuclei get flung to the bottom of the test tube
-form a pellet at the bottom of the test tube
-rest of the organelles stay suspended in the fluid above, the supernatent

-supernatent is drained off poured into another tube, and spun in the centrifuge at an even higher speed.
-process is repeated at higher and higher speeds until all the organelles are separated out.

38
Q

What are the 4 stages of the cell cycle?

A

Mitosis
Gap phase 1
Synthesis
Gap phase 2

39
Q

What happens during the gap phases?

A

Organelles and proteins making copies
Cell getting larger, growth

40
Q

What happens during synthesis?

A

DNA (chromosomes) making copies

41
Q

What is the structure of a chromosome?

A

A single stranded chromosome goes through interphase which results in two chromatids that are identical to each other being attached by a centromere in the centre

42
Q

What are the stages of mitosis?

A

Prophase
Metaphase
Anaphase
Telophase

43
Q

What happens during prophase?

A

-chromosomes condense, become visible
-centrioles (proteins) move to opposite ends of the cell (poles)
-nuclear envelope starts to break down
-chromosomes loose in cytoplasm

44
Q

What happens during metaphase?

A

-chromosomes line up on equator of cell (spindle equator)
-centrioles produce spindle fibres, attach to centromeres

45
Q

What happens during anaphase?

A

-spindle fibres start to contract, split centromere and chromatids are pulled to opposite poles
-sister chromatids moving to opposite poles of the spindle

46
Q

What happens during telophase?

A

-nuclear envelope wraps around chromosomes, reforms
-cytoplasm begins to divide
-chromosomes unfold

47
Q

What happens during cytokinesis?

A

-cell membrane splits
-formation of 2 genetically identical daughter cells

48
Q

Process of binary fission

A

Single circular DNA and plasmids go though DNA replication
Parent cell divided into two cells, with the cytoplasm roughly halved between the two daughter cells
Two daughter cells each contain a single copy of the circular DNA molecules and a variable number of plasmids

49
Q

what is the equation for serial dilutions?

A

C1V1 = C2V2
inital concentration X initail volume = final concentration X final volume

50
Q

What is the fluid mosaic model?

A

Fluid=
Phospholipid bilayer where each phospholipid can move relative to each other. The membrane id flexible with a constantly changing shape.

Mosaic=
Proteins embedded in the bilayer which vary in shap

51
Q

How does the cell membrane work when substances are trying to pass through?

A

Water soluble substances cannot move through phospholipid bilayer
Lipid soluble substances can diffuse through phospholipid bilayer.
Water is an exception, it is a very small polar molecule that can move through via osmosis

52
Q

What are surface proteins used for?

A

Mechanical support

53
Q

What is the function of the cholesterol attached to some of the phospholipids?

A

-hydrophobic
-helping phospholipid bilayer control what can and can’t go through
- add strength and stability
- makes a little less fluid and less flexible (reduces membranes permeability)
- if cholesterol wasn’t there too many substances would be able to move through.

54
Q

What is a channel protein?

A

Water filled Pore/ hole in the middle, allow certain substances through

55
Q

What is a carrier protein?

A

Allows large substances to bind, changes structure to allow them through

56
Q

What is the name of a substance with a carbohydrate on top of a protein?

A

Glycoprotein

57
Q

What is the name of a carbohydrate on top of a lipid?

A

Glycolipid
Phospholipid

58
Q

What is the function of a glycolipid?

A

Receptor for chemicals

59
Q

What is the function of a glycoproteins?

A

Receptors for hormones and neurotransmitters

60
Q

What are the two factors that affect the permeability of the cell surface membrane?

A

Temperature
Solvents / alcohol

61
Q

How does temperature affect the permeability of the cell surface membrane?

A

Under 0°C
- proteins denature
- holes in membrane
-not controlling what can diffuse through them

-ice crystals form
- when thawed they leave a hole

0 - 45°C
- low permeability

45°C +
- proteins denature
- holes in membranes
- phospholipids start to melt

62
Q

How do solvents / alcohol affect the permeability of the cell surface membrane?

A

Dissolve phospholipids

63
Q

What is the difference between plasma membranes and cell surface membranes?

A

Plasma membranes are partially permeable and refer to all membranes within the cell meanwhile cell surface membranes refer to membranes around the cell and are also partially permeable.

64
Q

What are the functions of the cell surface membrane?

A
  • controls what enter and leaves cells
  • allow different conditions inside and out of cells.
65
Q

What is the definition of diffusion?

A

The passive net movement of particles down a concentration gradient until equilibrium is reached.

66
Q

What is simple diffusion?

A

Lipid soluble, small, non polar molecules are able to diffuse through the phospholipid bilayer.

67
Q

What are factors that affect simple diffusion and how?

A

surface area
- larger surface area= faster diffusion
concentration gradient, difference between the high and low concentration
- larger concentration gradient = faster diffusion
diffusion pathway, pathway diffusion takes
- small diffusion pathway = diffusion happens faster
temperature
Increases= more kinetic energy

68
Q

What is facilitated diffusion and how does it work?

A

Substances diffusion through either channel proteins or carrier proteins.

Large molecules move through carrier proteins.
Large substances bind to carrier proteins.
Carrier protein change shape, substance usable to diffuse to other side of membrane.

Anything that is charged move through channel proteins.
Ions, polar molecules.

69
Q

What are factors that affect facilitated diffusion?

A

number of proteins
Not enough proteins for substances to bind to = slower rate of diffusion

concentration gradient

70
Q

Definition of osmosis?

A

The movement of water particles over a partially permeable membrane from a high water potential to a low water potential;

71
Q

What is water potential?

A
  • the pressure of water particles in a solution
  • kPa
  • pure water= 0 kPa
  • more negative number= lower water potential
72
Q

How does a cell behave in a hypertonic solution?

A
  • water move out of the cell as the water outside
  • has a lower water potential than inside so water moves out to the lower concentration from high
73
Q

How do cells behave in a hypotonic solution?

A
  • water moves into the cell by osmosis as the water potential inside the cell is lower than the water potential outside.
74
Q

What is a hypotonic solution?

A

When the water potential of a solution is more positive than the cell

75
Q

What is a hypertonic solution?

A

When the water potential of a solution is more negative than the cell

76
Q

How do cells behave in an isotonic solution?

A

Water does not move by osmosis as the water potential is the same both outside and inside the cell by osmosis

77
Q

What is active transport and its process?

A

The movement of particles from an area of low concentration to an area of high concentration across a cell membrane, using ATP and carrier proteins

For active transport to occur, the particle must bind to a specific site in the carrier protein.
On the inside of the cell, ATP also binds to the carrier proteins
The ATP is then hydrolysed to ADP and Pi which causes the carrier protein to change shape.
The carrier protein is now open to the other side of the membrane and the particle is released.
The phosphate molecule is then released from the carrier protein, which causes the carrier protein to return to its original shape.

78
Q

What is co transport and its process?

A

Cotransport uses ions to move substances into and out of cells. This occurs partially in epithelial cells of the ileum. Sodium and potassium ions are pumped out of the epithelial cells by active transport into blood leaving a lower concentration in the cell, causes these ions to move into the lumen by facilitated diffusion, which at the same time brings glucose and amino acids into the cell. These then diffuse from a high concentration in the epithelial cells by to a low concentration in the blood.

79
Q

What factors affect active transport?

A
  • respiration
  • density of carrier proteins

Biology (7 decks)

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