Cell Biology Flashcards
1
Q
Types of cell
A
- prokaryotic
- eukaryotic
2
Q
Prokaryotic cells
A
- single celled organism
- smaller than eukaryotic
- doesn’t contain membrane bound subcellular structures
3
Q
Eukaryotic cells
A
- organism made up of eukaryotic cells
- bigger than prokaryotic
- contains membrane bound subcellular structures
4
Q
Animal cell type
A
Eukaryotic
5
Q
Plant cell type
A
Eukaryotic
6
Q
Bacteria cell type
A
Prokaryotic
7
Q
Animal cell subcellular structures
A
- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes
8
Q
Nucleus
A
- contains cell DNA
- controls cell activity
9
Q
Cytoplasm
A
- where most chemical reactions take place
- contains enzymes to control reaction
10
Q
Cell membrane
A
Controls substances going in and out of the cell
11
Q
Mitochondria
A
Where energy is released through aerobic respiration
12
Q
Ribosomes
A
Where proteins are synthesised
13
Q
Plant cell subcellular structures
A
- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes
- cell wall
- permanent vacuole
- chloroplasts
14
Q
Cell wall
A
- supports and strengthens cell
- made of cellulose
15
Q
Permanent vacuole
A
Contains cell sap - weak solution of salt and sugars
16
Q
Chloroplasts
A
- where photosynthesis occurs
- contain chlorophyll which absorbs light for photosynthesis
17
Q
Bacteria subcellular structures
A
- cytoplasm
- cell membrane
- cell wall
- ribosomes
- plasmids
- strand of DNA floating in cytoplasm
18
Q
Plasmids
A
Small rings of DNA
19
Q
How do light microscopes work
A
Use light and lenses to form image of specimen and magnify it
20
Q
What can be viewed with light microscope
A
- individual cells
- large subcellular structures
21
Q
How do electron microscopes work
A
Use electrons to form an image
22
Q
What can be viewed with electron microscope
A
- internal structure of mitochondria and chloroplasts
- smaller things like ribosomes and plasmids
23
Q
Microscope with higher resolution
A
Electron
24
Q
Microscope with higher magnification
A
Electron
25
Magnification triangle
- AIM
- A - actual size
- I - image size
- M - magnification
26
Microscopy practical - prepare slide
- add water droplet to slide
- cut onion and use tweezers to peel epidermal tissue
- place tissue on water on slide
- add iodine to stain and highlight cell
- place cover slip on top by standing it upright beside slide, slowly tilt and lower on, avoid air bubbles
27
Microscopy practical - viewing
- clip slide to stage
- select lowest power objective lens
- use coarse focus knob to move stage up just below objective lens
- look down eyepiece, move stage down till in focus
- adjust fine focus knob to get clearer image
- use higher powered objective lens and refocus for greater magnification
28
Microscopy practical - drawing
- draw with sharp pencil
- use at least half space available
- draw clear, unbroken lines
- no colouring/shading
- draw subcellular structures in proportion
- write title and magnification
- label features with straight, uncrossed lines
29
Differentiation
Process by which a cell changes to become specialised for its job
30
When can animal cells differentiate
At an early stage
31
When can plant cells differentiate
All through their lives
32
What are most cells differentiated in mature animals used for
- repair
- replacing cells
33
Stem cells
Undifferentiated cells that can become specialised
34
Specialised animal cells
- sperm
- nerve
- muscle
35
Sperm cell function
Fertilise an egg cell to form an embryo
36
Sperm cell adaptations
- tail to aid movement
- many mitochondria to release energy for movement
- acrosome head released enzymes to digest egg membrane
- haploid nucleus contains genetic material for fertilisation
37
Nerve cell function
Carry electrical signals from one part of the body to another
38
Nerve cell adaptations
- long to cover large distances of the body quickly
- branched connections connect nerve cells together
- fatty myelin sheath to increase speed of messages travelling
39
Muscle cells function
Contract and relax to make bones move and joints bend
40
Muscle cells adaptations
- long so they have space to contract
- lots of mitochondria to generate release energy for contraction
41
Specialised plant cells
- root hair
- xylem
- phloem
42
Root hair cells function
- absorb water and minerals from soil
- hold plants in place as they grow
43
Root hair cell adaptations
Tiny hairs increase surface area for more absorption
44
Xylem cells function
Transport water from roots to other parts of the plant
45
Xylem cells adaptations
- die and ends break down to form hollow tubes for transportation
- thick cell walls support plant and hold it up for photosynthesis and reproduction
- made up of lignin to withstand high water pressures
46
Phloem cells function
Transport sugary water from leaves to rest of plant
47
Phloem cells adaptations
- they are sieve tubes that contain sieve plates
- few subcellular structures so more stuff can flow through
- next to companion cells with release energy for phloem
48
Where are chromosomes found
Nucleus
49
Chromosomes
Coiled up lengths of DNA molecules
50
Where are genes found
Chromosomes
51
How many copies of each chromosome in the body
2
52
How many chromosomes in a human cell
23 pairs
53
Why is cell cycle needed
- growth
- development
- repair
54
Stages of cell cycle
- growth and DNA replication
- mitosis
55
Cell cycle - growth and DNA replication
- DNA is spread out
- cell grows
- organelles copy
- DNA duplicates to form X shaped chromosomes (each arm is a copy)
56
Cell cycle - mitosis
- chromosomes line up
- cell fibres pull chromosomes arms to opposite ends of cell
- membranes form around chromosomes forming 2 nuclei
- cytoplasm and cell membrane divide
- 2 genetically identical daughter cells have been produced
57
What is mitosis
Division of nucleus
58
Stem cells
Undifferentiated cells that can differentiate into different types of cell based on what instructions they’re given
59
Types of human stem cell
- embryonic
- adult
60
Where are human stem cells found
- embryos
- bone marrow
61
Embryo
Resulting ball of cells formed after an egg cell is fertilised by a sperm cell
62
Embryonic stem cells
- found in early human embryos
- can turn into any type of cell
63
Where are adult stem cells found
Bone marrow
64
Bone marrow stem cells
- found in adults
- can only turn into certain types of cell, like blood
65
Uses of stem cells
- medicine
- research
66
Examples of conditions stem cells can treat
- diabetes
- paralysis
67
How are stem cells clones produced
Grown in a lab
68
Therapeutic cloning
Stem cells being made to have the same genetic information as a patient so they have the same genes and won’t be rejected by the body
69
Risks of using stem cells in medicine
Stem cells grown in a lab may become contaminated with a virus which is passed on to the patient, making them sicker
70
Arguments against stem cell research
- human embryos shouldn’t be used for experiments as they are potential human life
- scientists should concentrate on finding and developing other sources of stem cells so people can be helped without using embryos
71
Arguments for stem cell research
- curing suffering patients is more important than rights of embryos
- embryos used for research are usually unwanted in fertility clinic so would be destroyed anyway
72
Where are stem cells found in plants
Meristem
73
Where are meristems in plants
Tips of plant roots and shoots
74
What types of plant cell can meristem tissue differentiate into
Any
75
Uses of plant stem cells
- produce clones of a plant quickly and cheaply
- used to grow more plants of a rare species to stop them being wiped out
- grow crops of identical plants with desired features, like disease resistance
76
Diffusion
The net movement of particles from an area of higher concentration to an area of lower concentration
77
In what substances does diffusion occur
- solutions
- gases
78
Why does diffusion occur in solutions and gases
The particles are free to move around randomly
79
What increases rate of diffusion
- larger concentration gradient
- higher temperature
- larger surface area
80
What can diffuse through cell membranes
Small molecules like oxygen, glucose, amino acids, water
81
What can’t diffuse through cell membranes
Big molecules like starch and proteins
82
Osmosis
The net movement of water molecules from through a partially permeable membrane from an area of higher water concentration to an area of lower water concentration
83
Partially permeable membrane
A membrane with very small holes in it so small molecules and pass through and big molecules can’t
84
Osmosis practical
- cut potato into identical cylinders and measure mass
- place them into sugar solutions of different concentrations including pure water for 24 hours
- take them out, dry with paper towel, measure mass again
- calculate percentage change in mass
- if water moved in by osmosis, mass with have increased
85
Active transport
The net movement of particles from an area of lower to higher concentration, requiring energy
86
What do plants need mineral ions for
Healthy growth
87
How do root hair cells absorb mineral ions
Active transport
88
Why do root hair cells use active transport to absorb mineral ions
The concentration of minerals is usually higher in the root hair cell than in the soil
89
How do root hair cells absorb water from soil
Osmosis
90
How are nutrients absorbed from the gut to the blood
Usually active transport
91
Larger organism’s SA:V
Smaller
92
How are exchange surfaces adapted
- thin membrane - shorter diffusion distance
- large surface area - lots of substances can diffuse at once
- animal exchange surfaces have lots of blood vessels - gets stuff in an out of blood quickly
- animal gas exchange surfaces are well ventilated - gets air in and out
93
Job of lungs
Transfer oxygen to blood and remove waste carbon dioxide from it
94
Alveoli
Little air sacs where gas exchange takes place in the lungs
95
Alveoli specialisations
- large surface area
- moist lining for dissolving gases
- very thin walls
- good blood supply
96
Villi function
Increase surface area in small intestine so digested food can be absorbed into blood faster
97
Villi adaptations
- single layer of surface cells
- good blood supply for quick absorbtion by maintaining concentration gradient
98
How does carbon dioxide get into leaves
- diffuses through stomata
- diffuses into air spaces
- diffuses into cells where photosynthesis happens
99
Where is the exchange surface on a leaf
Underneath
100
Where are stomata on a leaf
Underneath
101
How does oxygen leave the leaf
Diffuses through the stomata
102
What controls the size of the stomata
Guard cells
103
When do stomata close
If a plant is losing water faster than it’s being replaced by the roots
104
What would happen to a plant without guard cells
Wilting
105
Why does leaf have a flattened shape
Increase area of exchange surface so it’s more effective
106
What do cell walls inside leaf do
Form another exchange surface
107
Purpose of air space in leaf
Increase surface area of exchange surface formed by cell walls so there’s more chance for carbon dioxide to get into cells
108
How does water vapour leave the leaf
- evaporates from the cells inside the leaf then diffuses out the stomata as there is more inside the leaf than the air outside
- some leaves via the leaf surface
109
Exchange surface in fish
Gills
110
How do fish get oxygen
- water containing oxygen enters through the mouth and passes into gills
- oxygen diffuses from water to blood
- carbon dioxide diffuses from blood to water
111
What are gills made of
Thin plates of gill filaments
112
Purpose of gill filaments
Increase surface area of gills for exchange of gases
113
What are gill filaments covered with
Lamallae
114
How do lamellae speed up diffusion
- increase surface area of gills
- have lots of blood capillaries
- thin surface layer of cells to minimise diffusion distance
115
What happens in lamellae
Blood flows through one direction and water flows through the other to maintain a large concentration gradient between them
116
Where is the concentration of oxygen highest in fish gas exchange
Water so as much oxygen can diffuse into the blood as possible
117
Why might data be done per 100000 not whole population
So figures can be compared - likely different total population numbers
