Unit 1: Chapter 1 + 2 Flashcards Preview

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Flashcards in Unit 1: Chapter 1 + 2 Deck (81):
1

Cells

Are the basic structural and functional units of life, all living organisms are built of one or more cells.

2

How big are cells?

Most cells are microscopic, only a few such as a human egg cell and amoeba can be seen with the naked eye.

3

Animal cell size

10-40 micrometres.

4

Red blood cell size

6-8 micrometres.

5

Plant cell size

10-100 micrometres

6

Virus size

20-300 nanometres

7

Are viruses living or non-living?

Both, because of they;
don't have a structure
cannot carry out metabolic activities
cannot self-replicate

8

Shape and functions

The size of the cells vary and therefore impacts on function

9

Motor neuron cells

- Star-shaped
- Have a long axon
- Transmit nerve impulses from a person's spinal cord to voluntary muscles

10

Smooth muscle cells

- Contain proteins that crisscross the cell and when contracted they shorten
- Found in the gut wall, walls of blood vessels and uterus

11

Shapes of microbial cells

Rod-shaped
Corkscrew-shaped
Spherical

12

Are there fixed shapes?

No, some cells are able to move actively and therefore have a flexible plasma membrane

13

Cells capable of self-propelled movement

- Cancer cells
- White blood cells
- Amoebas

14

Site of exchange

Plasma membrane - where materials are moved in and out of a cell to maintain essential functions

15

Rate of exchange

Must be quick enough that the materials are delivered fast enough but slow enough to avoid accumulation of materials

16

Surface area to volume ratio

Is the surface area of a plasma membrane available to supply material or remove wastes from the cytoplasm of a cell

17

Rules of SA: V ratio

As an object increases in size the SA: V ratio gets smaller
As an object decreases in size the SA: V ratio gets bigger
The higher the ratio the greater the efficiency of the exchange

18

Why are cells so small?

Beyond a given cell size, the 2-way exchange of materials across the plasma membrane cannot occur fast enough to sustain the volume of the cell contents

19

Prokaryote

Any cells or organisms without a membrane-bound nucleus (bacteria and archea)
-typically smaller (1-2 micrometres)
-DNA is dispersed
-Unicellular

20

Eukaryotes

Cell or organism with a membrane-bound nucleus (plants, animals, fungi)
-typically larger (10-100 micrometres)
-DNA stored as chromosomes in the nucleus
-Unicellular/Multicellular

21

Similarities between eukaryotes and prokaryotes

Both have;
- ribosomes
- cell membrane
- cytosol
- vacuole

22

Cytoskeleton

3D networks of fine protein filaments and microtubules within the cell, to give it support and structure
- determines cell chape
- moves chromosomes during cell division

23

Organelles not enclosed in membranes

Ribosomes
Cilia and flagella
Centrioles

24

Animal cell organelles

Nucleus
Mitochondria
Nuclear envolope
Nucleoulus
Ribosome
ER (smooth and rough)
Lysosome
Centriole
Protein microtubule
Golgi apparatus
Vesicle
Peroxisome
Endosome
Plasma membrane

25

Plant cell organelles

Nucleus
Nucleolus
Mitochondria
Ribosomes
Endoplasmic reticulum
Plasma membrane
Cell wall
Microtubule
Vacuole
Chloroplast
Peroxisome
Vesicle
Golgi apparatus
Lysosome

26

Difference between animal and plant cell

Animals lack a cell wall, chloroplast and large central vacuole

27

Cell wall

Plant cell
Outside cell membrane
Fully permeable
Provides strength and support to cells
Prevents over expansion of cells from osmosis
Made of cellulose

28

Cytosol

The fluid region in which the organelles exist

29

Which cells have secondary cell walls?

Woody plants and perennial grasses

30

Nucleus

Membrane bound organelle that controls the function of plant and animal cells
- has a double membrane (nuclear envelope)
- contains chromatin (DNA)

31

Nucleolus

Small part of the nucleus that makes ribosomes

32

Multinucleate

Many nucleus

33

Mitochondria

The site of cellular respiration
In animal and plant cells
Produces ATP for the cell to use as energy

34

Cellular respiration equation

O2 + C6H12O6 -> CO2 + H2O + ATP
Oxygen + Glucose -> Carbon dioxide + Water + Energy

35

Why would a cell need more mitochondria?

A cell that requires more energy

36

Ribosomes

Where amino acids are assembled to make proteins
In plant and animal cells
Attached to the Rough ER
Free floating

37

Rough endoplasmic reticulum

Organelle consisting of membrane-bound channels that transport substances within a cell with ribosomes attached to the outside
- transports proteins within the cell
- makes glycoproteins
- folding proteins
- assembling proteins (ribosomes)
- plants and animals

38

Smooth endoplasmic reticulum

Organelle consisting of membrane-bound channels that transport substances within a cell
- synthesises and transports lipids
- manufactures, detoxifies, stores and transports products
- plants and animals

39

Golgi complex

Organelle that packages material into vesicles for export from a cell
- transported from Rough ER in transition vesicles
- transported from Golgi body in secretory vesicles, merge with the plasma membrane and are excreted
-plants and animals

40

Lysosomes

A fluid-filled sac that contains digestive enzymes to break down excess macromolecules, old cell organelles and break down of substances
- animal and plant

41

Peroxisomes

The organelle containing enzymes that detoxify various toxic materials that enter the bloodstream
- oxidise fatty acids
- break down long chain fatty acids
- plants and animals

42

Chloroplasts

Organelle that converts light into energy for the cell to use
- contains chlorophyll (green colour)
- only in plant cells

43

Why is chloroplast only in some plant cells?

Because it converts energy from sunlight and therefore has to be exposed to light

44

Cilia

Cilia are short, hair like appendages extending from the surface of a living cell.
- short
- eukaryotic cells

45

Flagella

Flagella are long, threadlike appendages on the surface of a living cell.
- long
- Eukaryotic and prokaryotic cells

46

Difference between the plasma membrane and the cell membrane

Plasma membrane is the layer surrounding the organelles and the cell whereas the cell membrane is the layer surrounding the cell

47

Plasma membrane

AKA cell membrane
The partially permeable boundary of the cell separating it from its physical surroundings

48

Structure of the plasma membrane

2 major components;
Phospholipids - bilayer
Proteins

49

Phospholipids

2 fatty acids joined to a phosphate group
Contains hydrophilic head (phosphate)
contains hydrophobic tail (fatty acid )

50

The hydrophilic and Hydrophobic arrangement

Hydrophilic heads are exposed to the external/internal
Hydrophobic tails face each other

51

Why is the plasma membrane flexible?

due to the fatty acids which are fluids and therefore flexible. this enables them to change shape

52

2 different types of proteins

Integral
Peripheral

53

Integral proteins

Are transmembrane (span the width of the membrane)
have protein exposed on both sides

54

Glycoprotein

When carbohydrate groups are attached to the exposed part of the protein on the external side

55

Peripheral proteins

Anchored to the exterior of the membrane

56

Functions of the plasma membrane

Active and selective boundary
Denotes cell identity
Receives external signals
Transports materials

57

Factors that affect substances crossing the membrane

Size
Presence of charge (polar)
Solubility in lipids
Direction of concentration gradient

58

Molecular size

Some molecules are too big to fit across the membrane, the smaller ones can fit through the gaps

59

Presence of a charge (polar)

The bilayer is non-polar and therefore charged ions cannot cross the membrane

60

Solubility in lipids

Lipophilic molecules can cross easily but hydrophilic molecules cannot cross due to being repelled by water

61

Direction of concentration gradient

Movemnet agaisnt the concetration gradient requires energy and is much harder than with the concentration gradient

62

Ways of crossing the boundary

Simple diffusion
Facilitated diffusion
Active transport
Endocytosis/exocytosis

63

Simple diffusion

Movement of substances across the membrane from a region of high concentration to low concentration
- passive
- aims for equal concentration on both sides
- across a semi permeable membrane or not

64

Osmosis

Movement of water across a semipermeable membrane
- From an area of higher water to an area of lower water
- From an area of low concentration to higher concentration

65

Hypotonic

having lower solute concentration than the cell contents

66

Isotonic

Having an equal solute concentration to that of the cells

67

Hypertonic

Having higher solute concentration than the cell contents

68

Water content in animal cells

Too much causes it to burst
Less causes it to shrink

69

Water content in plant

Too much causes membrane to swell and cell wall prevent breakage
Too little water causes the plasma membrane to break away from the cell wall

70

Facilitated diffusion

It is diffusion that is enabled by special protein transporters in the membrane, allows molecules that can not diffuse across the plasma membrane through channel proteins or carrier proteins
- passive

71

Channel proteins

They are transmembrane and have a pore that aloows charged particles through

72

Carrier proteins

Is a specific size and shape to allw certain particles through, acting like a gate

73

Photosynthesis equation

6CO2 + 12H2O -> C6H12O6 + 6O2 + 6H2O

74

Rates of diffusion (simple)

The higher the concentration gradient the faster the substance will move by simple diffusion across a plasma membrane.

75

Rates of diffusion (facilitated)

The higher the concentration gradient the faster a substance will move across a membrane to a certain point when all the transporters are fully occupied.

76

Active transport

Moving dissolved substances from an area of low concentration to an area of high concentration
- active (requires energy)

77

Endocytosis

Is bulk transport of material into a cell
phagocytosis - solid
pinocytosis - fluid
Energy requiring process

78

Exocytosis

Bulk transport of material out of the cell
Energy required
Use of golgi body

79

Different microscopes

Light (optical) microscope
Electron (transmission) microscope

80

Differences between microscopes

Optical has lower levels of resolution and magnification
Optical is coloured, electron is b/w
Optical can be used for living cells

81

What organelles can not be seen with light microscope?

Ribosomes
Mitochondria
Peroxisomes