Unit 1: Chapter 1 + 2 Flashcards Preview

Biology Unit 1+2 > Unit 1: Chapter 1 + 2 > Flashcards

Flashcards in Unit 1: Chapter 1 + 2 Deck (80):
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

Are viruses living or non-living?

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

4

Shape and functions

The size of the cells vary and therefore impacts on function

5

Motor neuron cells

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

6

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
Can generate sustained involuntary contractions

7

Shapes of microbial cells

Rod-shaped
Corkscrew-shaped
Spherical

8

Are there fixed shapes for all cells?

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

9

Cells capable of self-propelled movement

Cancer cells
White blood cells
Amoebas

10

Site of exchange

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

11

Rate of exchange

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

12

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

13

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

14

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

15

Prokaryote

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

16

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

17

Similarities between eukaryotes and prokaryotes

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

18

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

19

Organelles not enclosed in membranes

Ribosomes
Cilia and flagella
Centrioles

20

Animal cell organelles

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

21

Plant cell organelles

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

22

Difference between animal and plant cell

Animals lack a cell wall, chloroplast and large central vacuole

23

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

24

Cytosol

The fluid region in which the organelles exist

25

Which cells have secondary cell walls?

Woody plants and perennial grasses

26

Nucleus

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

27

Nucleolus

Small part of the nucleus that makes ribosomes

28

Multinucleate

Many nucleus

29

Mitochondria

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

30

Cellular respiration equation

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

31

Why would a cell need more mitochondria?

A cell that requires more energy ie; muscle cell

32

Ribosomes

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

33

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

34

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

35

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

36

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

37

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

38

Chloroplasts

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

39

Why is chloroplast only in some plant cells?

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

40

Cilia

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

41

Flagella

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

42

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

43

Plasma membrane

AKA cell membrane
The partially permeable boundary of the cell separating it from its physical surroundings
Can exclude some substances from entering the cell while permitting entry of others

44

Structure of the plasma membrane

2 major components;
Phospholipids - bilayer
Proteins

45

Phospholipids

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

46

The hydrophilic and Hydrophobic arrangement

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

47

Why is the plasma membrane flexible?

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

48

2 different types of proteins

Integral
Peripheral

49

Integral proteins

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

50

Glycoprotein

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

51

Peripheral proteins

Anchored to the exterior of the membrane

52

Functions of the plasma membrane

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

53

Factors that affect substances crossing the membrane

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

54

Molecular size

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

55

Presence of a charge (polar)

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

56

Solubility in lipids

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

57

Direction of concentration gradient

Movement against the concetration gradient requires energy and is much harder than with the concentration gradient

58

Ways of crossing the boundary

Simple diffusion
Facilitated diffusion
Active transport
Endocytosis/exocytosis

59

Simple diffusion

Net movement of substances across the membrane from a region of high concentration to low concentration until it reaches an equilibrium
- passive
- aims for equal concentration on both sides
- across a semi-permeable membrane
- for smaller, uncharged atoms

60

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

61

Hypotonic

having lower solute concentration than the cell contents

62

Isotonic

Having an equal solute concentration to that of the cells

63

Hypertonic

Having higher solute concentration than the cell contents

64

Water content in animal cells

Too much causes it to burst
Less causes it to shrink

65

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

66

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

67

Channel proteins

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

68

Carrier proteins

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

69

Photosynthesis equation

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

70

Rates of diffusion (simple)

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

71

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.

72

Active transport

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

73

Endocytosis

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

74

Exocytosis

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

75

Different microscopes

Light (optical) microscope
Electron (transmission) microscope

76

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

77

What organelles can not be seen with light microscope?

Ribosomes
Mitochondria
Peroxisomes

78

Living organisms can only exist where;

There is an energy source
Liquid water
Chemical building blocks (C,O,N,H)
Stable environmental conditions

79

Difference between prokaryotic and eukaryotic cells?

A prokaryotic cell is a very simple cell which contains no membrane-bound organelles and has a nucleoid which is circular DNA whereas a eukaryote is a very complex cell with many membrane-bound organelles

80

How does the cell maintain its essential functions

A constant exchange of material between the cell and its external environment