Cell Structure 1.1 Flashcards
(119 cards)
1
Q
What are two types of cells
A
Eukaryotic (plant and animal)
Prokaryotic (bacteria)
2
Q
What are the differences between eukaryotic and prokaryotic cells
A
Prokaryotic cells are much smaller than eukaryotic cells.
Eukaryotic cells contain membrane bound-organelles and a nucleus containing genetic material, while prokaryotic do not.
3
Q
What is the prokaryotic cell wall composed of
A
Peptidoglycan
4
Q
How is genetic information stored in a prokaryotic cell
A
In a single DNA loop in the cytoplasm
5
Q
What are plasmids
A
Small, circular loops of DNA found free in the cytoplasm and separate from the main DNA
carry genes that provide genetic advantages e.g. antibiotic resistance
6
Q
What is order of magnitude
A
A power to the base 10 used to quantify and compare size
7
Q
What is centimetre (cm)
A
1 x 10 ^ -2 meters
8
Q
What is a millimetre (mm)
A
1 x 10 ^ -3 meters
9
Q
What is a micrometer (um)
A
1 x 10 ^ -6 meters
10
Q
What is a nanometer (nm)
A
1 x 10 ^ -9 meters
11
Q
What is the difference in order of magnitude between a human hair (100 um) and the HIV virus (length = 100 nm)
A
100 um = 10 ^ -4 m
100 nm = 10 ^ -7 m
-4-(-7) = -4 + 7 = 3
12
Q
List the components of both plant and animal cells
A
Nucleus, cytoplasm, cell membrane, mitochondria and ribosomes
13
Q
List the additional cell components found in plant cells
A
Chloroplast, permanent vacuole and cell wall
14
Q
Other than storing genetic information, what is the function of the nucleus
A
Controls cellular activities
15
Q
Describe the structure of the cytoplasm
A
Fluid component of the cell
Contains organelles, enzymes and dissolved ions and nutrients
16
Q
What is the function of the cytoplasm
A
Site of cellular reactions e.g. first stage of respiration
Transport medium
17
Q
What is the function of the cell membrane
A
Controls the entry and exit of materials into and out of the cell
18
Q
What is the function of the mitochondria
A
Site of later stages of aerobic respiration in which ATP is produced
19
Q
What is the function of ribosomes
A
Joins amino acids in a specific order during translation for the synthesis of proteins
20
Q
What is the plant cell wall made of
A
Cellulose
21
Q
What is the function of the plant cell cell wall
A
Provides strength
Prevents the cell bursting when water enters by osmosis
22
Q
What does the permanent vacuole contain
A
Cell sap (a solution of salts, sugars and organic acids)
23
Q
What is the function of the permanent vacuole
A
Supports the cell, maintaining its turgidity
24
Q
What is the function of chloroplast
A
Site of photosynthesis
25
Describe how sperm cells in animals are adapted to their function
Haploid nucleus contains genetic information
Tail enables movement
Mitochondria provide energy for tail movement
Acrosome contains enzymes that digest the egg cell membrane
26
Describe how nerve cells in animals are adapted to their function
Long axon allows electrical impulses to be transmitted all over the body from the central nervous system
Dendrites from the cell body connect to and receive impulses from other nerve cells, muscles and glands
Myelin sheath insulates the axon and speed up the transmission of impulses along the nerve cell
27
Describe how muscle cells in animals are adapted to their function
Arrangement of protein filaments allows them to slide over each other to produce muscle contraction
Mitochondria to provide energy for muscle contraction
Merged cells in skeletal muscle allow muscle fibre contraction in unison
28
Describe how root hair cells in plants are adapted to their function
Large surface area to absorb nutrients and water from surrounding soil
Thin walls that do not not restrict water absorption
29
Describe how xylem cells in plants are adapted to their function
No upper or lower margins between cells to provide a continuous route for water to flow thick, woody side wide strengthen their structure and prevent collapse
30
Describe how phloem cells in plants are adapted to their function
Sieve plates let dissolve amino acids and sugars be transported up and down the stem
Companion cells provide energy needed for active transport of substances along the phloem
31
What is cell differentiation
The process by which cells become specialised
32
Why is cell differentiation important
Allows production of different tissues and organs that perform various vital functions in the human body
33
At what point in their life cycle do most animal differentiate
Early in their life cycle
34
For how long do plant cells retain the ability to differentiate
Throughout their entire life cycle
35
What is the purpose of cell division in mature animals
Repair and replacement of cells
36
What changes does a cell go through as it differentiates
Becomes specialised through acquisition of different sub-cellular to enable a special function to be performed by the cell
37
Define magnification
The number of times bigger an image appears compared to the size of the real object
38
Define resolution
The smallest distance between two objects that can distinguished
39
How does a light microscope work
Passes a beam of light through a specimen which travels through the eyepiece lens, allowing the specimen to be observed
40
What are the advantages of light microscopes
Inexpensive
Easy to use
Portable
Observe both dead and living specimens
41
What is the disadvantage of light microscopes
Limited resolution
42
How does an electron microscope work
It uses a beam of electrons which are focused using magnets. The electrons hit a fluorescent screen which emits visible light, producing an image.
43
Name the two types of electron microscope
Transmission electron mission (TEM)
Scanning electron microscope (SEM)
44
What is the advantage of electron microscope
Greater magnification and resolution
45
Why do electron microscopes have a greater magnification and resolution
They use a beam of electrons which has a shorter wavelength than photons of light
46
How have electron microscopes enabled scientists to develop their understanding of cells
Allows small sub-cellular structures (e.g. mitochondria, ribosomes) to be observed in detail
Enable scientists to develop more accurate explanations about how cell structure relates to function
47
What are disadvantages of electron microscopes
Expensive
Large so less portable
Require training to use
Only dead specimens can be observed
48
How can the magnification of an image be calculated
Magnification = size of image / size of real object
49
What is standard form
A way of expressing numbers - written as figure between 1 and 10 multiplied by a positive or negative power of 10
50
Write 0.005 in standard form
0.005 = 5 x 10 ^ -3
51
What nutrients make up a nutrient both solution
All nutrients required for bacteria to grow including nitrogen for protein synthesis, carbohydrates for energy and other minerals.
52
Describe the preparation of an uncontaminated culture using aseptic technique,
1. Use pre-sterilised plastic Petri dishes or sterilise glass Petri dishes and agar gel before using with an autoclave
2. Pour the sterile agar gel into the Petri dish and allow time to set
3. Sterilise the inoculating loop by passing it through a Bunsen burner flame
4. Dip the inoculating loop into the solution of microorganisms and make streaks with the loop on the surface of the agar
5. Put the lid on the Petri dish and secure it with tape. Label accordingly then turn and store upside down.
6. Incubate the culture at 25*C in school laboratories
53
Why must Petri dishes and culture media before sterilised before use
To kill any bacteria already present
54
Why must inoculating loops be sterilised by passing them though Bunsen burner flame
To kill any bacteria present on the inoculating loop
55
What is active transport
The movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient) with the use of energy from respiration
56
What is the adult stem cell
A type of stem cell that can form many types of cells
57
What is agar jelly
A substance placed in Petri dishes which is used to culture microorganisms on
58
What is cell differentiation
The process where a cell becomes specialised to its function
59
What is the cell membrane
A partially permeable barrier that surrounds the cell
60
What is the cell wall
An outer layer made of cellulose that strengthens plant cells
61
What is chloroplast
An organelle which is the site of photosynthesis
62
What is chromosomes
DNA structures that are found in the nucleus which are made up of genes
63
What is concentration gradient
The difference in concentration between two area
64
What is diffusion
The spreading of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration
65
What is the Eukaryotic cell
A type of cell found in plants and animals that contains a nucleus
66
What is magnification
How much bigger an image appears compared to the original object
67
What is the Meristematic cells
A type of stem cell that can differentiate into any type of plant cell
68
What is mitochondria
An organelle which is the site of respiration
69
What is mitosis
A type of cell division which produces two genetically identical daughter cells from one parent cell
70
What is the nucleus
An organelle found in most eukaryotic cells that contains the genetic material of the cell and controls the activities of the cell
71
What is the organelle
A specialised structure found inside a cell
72
What is osmosis
The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
73
What is the plasmid
Loops of DNA found in bacteria that does not contain a nucleus
74
What is the prokaryotic cell
A type of cell found in bacteria that does not contain a nucleus
75
What is resolution
The ability to distinguish two different points in a specimen
76
What are specialised cells
Cells that are adapted to perform a specific function
77
What is a stem cell
An undifferentiated cell that can divide to produce many specialised cells of the same type
78
What is the surface area
The amount of contact an object has with its environment
79
What is the surface area to volume ratio (SA:V)
The size of the object compared with the amount of area where it contains it’s environment
80
What is the cell cycle
A series of stages prepare in the cell for division
81
What is therapeutic cloning
Producing an embryo that has the same genes as a patient
82
What is the permanent vacuole
An organelle that stores cell sap
83
In cell division what do the body produce new cells for
Growth
Replace worn out cells
Repair damaged tissue
84
In multicellular organisms what do new cells produce
In multicellular organisms new cells are produced in process called the cell cycle
85
Largest to smallest cells
Cell, nucleus, chromosomes, DNA, gene
86
What does each cell have
Nucleus
87
What does the nucleus contain
Chromosomes
88
What are chromosome made up of
DNA and carry genes
89
What does a gene control
A characteristic
90
Chromosomes are copied during the cell cycle. Where are chromosomes found?
Nucleus
91
What is the name of a section of a chromosome that controls a characteristic
Gene
92
During mitosis cells need extra energy, which cell structures provide most of this energy?
Mitochondria
93
Why is mitosis important in living organisms
To repair tissues
94
Name the type of cell division that produces genetically identical body cells for growth and repair
Mitosis
95
What happens at stage 1 of the cell cycle
Chromosomes replicate
96
What happens at stage 2 of the cell cycle
Chromosome is pulled
97
What happens at stage 3 of the cell cycle
Cytoplasm and cell membrane divides (to 2 cells)
98
What is an stem cell
An undifferentiated/unspecialised cell
99
Why can stem cells divide
To provide more stem cells of the same type OR did types of specialised cell through differentiation
100
Where do human stem cells come from
1. Human embryos (embryonic stem cells)
2. Adult bone marrow (adult stem cells)
101
Advantages of embryonic stem cells
1. Can develop into almost every type of cell
2. Can treat a wide variety of diseases
3. Easily available - leftover IVF embryos
4. Painless
102
Disadvantages of embryonic stem cells
1. Ethical issues - destruction of the embryo since the embryo cannot consent - right to life
2. Relatively untested/unreliable
3. Risk of cancer developing
4. Long term side effects unknown
103
Advantages of adult stem cells
1. Patent gives consent
2. Quick recovery
3. Relatively safe - low risk to donor
4. Well tested/reliable
104
Disadvantages of adult stem cells
1. Operation risks - infection
2. Produces a limited range of cells
3. Only a few diseases treated
4. Painful procedure
5. Risk of rejection if not from patient
105
Stem cells can be used to treat some diseases. What is a stem cell?
An undifferentiated cell. Change into other types of cells.
106
Stem cells have the potential to treat the following conditions
1.Paralysis from spinal injuries - replace damaged nerve cells
2. Type 1 diabetes - replace insulin producing cells in the pancreas
107
What happens in therapeutic cloning
An embryo is produced with the same genes as the patient
108
Order of therapeutic cloning
1. Nucleus taken out of a human egg cell
2. Nucleus from a patients cell put into the egg cell
3. Egg cell stimulated to divide and develop into an embryo
4. Stem cells taken from the embryo after 4-5 days
5. Stem cells grown in a container of warm nutrients
6. Stem cells treated to develop into required cell types for a patient
109
Advantages of therapeutic cloning
1. Used to treat diseases/replace organs or tissues
2. Produces many different types of cells and tissues
3. Many cells produced
4. Reduces waiting time for organs transplants
5. Cells could be used for research
110
Disadvantages of therapeutic cloning
1. Potential life destroyed
2. Shortage of eggs/egg donors
3. Egg donation has risks/side effects
4. Long term effects not known/untested
5.may cause tumours
6. Risk of vital transfer
111
Stem cells divide by mitosis. Scientists can use stem cells from an embryo to create heart cells in a laboratory. Which organ system contains heart cells?
Circulatory system
112
One medical condition that could be treated using heart cells created from an embryo
Heart disease
113
One reason why a patient may not want to be treated with heart cells created from an embryo
They won’t know the long term effects
114
Name two pieces of laboratory equipment a student could have used to prepare cells to view using a microscope
1. Slide
2. Cover slip
115
Describe how alveoli and the villi are adapted to increase absorption
Both have a large surface area to maximise diffusion. Both have thin walls to reduce distance. Good blood supply to maintain gradient. Villi have microvilli to increase surface area.
116
Stage 1 in the cell cycle
Cell grows and prepares for cell division. DNA is replicated. This is the longest stage in the cell cycle.
117
Stage 2 in the cell cycle
The chromosomes are separated and the nucleus divides.
118
Stage 3 in the cell cycle
The cytoplasm and the cell membrane also divide to form two identical daughter cells.
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