B2.1 The building blocks of cells Flashcards
1
Q
What does a light microscope do?
A
It magnifies an object
2
Q
What does the cell membrane do?
A
- separate the contents of the cell from its surroundings
- controls the movement of substances into and out of the cell
3
Q
What process happens in the cytoplasm?
A
Respiration
4
Q
What are the seven life processes?
A
Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition
5
Q
What does the nucleus do?
A
Control the activities of the cell
6
Q
What happens in the mitochondria?
A
Respiration
7
Q
What does the cell wall do?
A
Support the cell and allow it to keep its shape
8
Q
What are plant cell walls made of?
A
Cellulose
9
Q
What is the vacuole?
A
A space in the cytoplasm that is filled with cell sap
10
Q
What does the vacuole do?
A
Helps support the plant by keeping the cells rigid
11
Q
What does a chloroplast do?
A
Absorbs light energy to be used in photosynthesis
12
Q
What green substance does the chloroplast use to absorb light energy?
A
Chlorophyll
13
Q
What is the word equation for photosynthesis?
A
carbon dioxide + water (+ light energy) → glucose + oxygen
14
Q
What is the magnification of a light microscope?
A
x1500
15
Q
What is the magnification of an electron microscope?
A
x2,000,000
16
Q
Do bacteria have a nucleus?
A
No
17
Q
What two types of DNA do bacteria contain?
A
- Chromosomal DNA
- Plasmid DNA
18
Q
What is the giant loop of DNA that carries most of the genetic material in a bacterial cell called?
A
Chromosomal DNA
19
Q
What type of DNA comes in small loops and carries extra genetic information in a bacterial cell?
A
Plasmid DNA
20
Q
What are flagella?
A
Long whip-like structures that the bacteria can use to move themselves along
21
Q
Where are chromosomes found?
A
The nucleus
22
Q
What are chromosomes made up of?
A
A string of genes
23
Q
What do genes contain instructions for?
A
Amino acids
24
Q
What is a gene made up of?
A
A length of DNA
25
What causes genetic disorders?
A faulty allele
26
What is gene therapy?
Replacing or mending faulty genes that cause a disorder
27
What is genetic engineering?
The removal of a gene from one organism and inserting it into the DNA of another
28
What does GMO stand for?
Genetically modified organism
29
What are some advantages of genetically modified bacteria producing insulin?
- Can be used by vegans (used to be extracted from dead cattle and pigs)
- supply of insulin is not affected by animal diseases or the number of animals slaughtered for meat
- by using bacteria in fermenters insulin can be made cheaply in vast quantities
30
What is a disadvantage of genetically modified bacteria producing insulin?
Bacteria produce insulin slightly differently so it does not suit everyone because of minute differences
31
Why do humans need beta-carotene?
To produce vitamin A
32
What are the effects of a lack of vitamin A?
- the immune system doesn't work properly which may cause death
- may cause blindness
33
Why are some people concerned about GM foods?
- believe it might crossbreed and contaminate the original DNA of the plant
- worry it might harm people
34
What are some disadvantages of genetically modified food?
- expensive
| - some don't produce fertile seed
35
What are some disadvantages of making herbicide resistant crops?
- the development of herbicide resistant weeds because of cross-pollination with wild plants
- there may be a loss of biodiversity as fewer weeds survive, meaning loss of food and shelter for animals
36
How many chromosomes do human diploid cells contain?
46 (2 pairs of 23)
37
When is mitosis used?
During growth or to replace damaged cells
38
What is DNA replication?
Chromosomes making copies of themselves
39
How do you produce two daughter cells?
Through the division of a parent cell
40
How many cells does mitosis produce?
Two
41
How many cells does meiosis produce?
Four
42
What process is used in the asexual reproduction of bacteria?
Mitosis
43
What is produced when two gametes fuse during fertilisation?
A diploid cell called a zygote
44
What is a zygote that develops into a ball of cells called?
An embryo
45
How many chromosomes does a haploid cell have?
23
46
Does meiosis or mitosis produce genetically identical cells?
Mitosis
47
What are clones?
Individuals that are genetically identical
48
What is a way of producing cloned animals?
Nuclear transfer
49
What does enucleated mean?
Something that has had its nucleus removed
50
What happens during nuclear transfer?
- the nucleus of a body cell is put into an enucleated egg cell
- it is stimulated to start dividing to form an embryo. -it is then implanted into the uterus of the surrogate mother
51
How is a cell stimulated to start dividing into an embryo during nuclear transfer?
Through electric pulses
52
What are embryonic stem cells?
Cells from an embryo in the early stages of division that can differentiate into almost any type of cell
53
What two things can happen when a stem cell divides?
It can produce more stem cells or it can produce specialised or differentiated cells
54
What is the difference between adult stem cells and embryonic stem cells when they differentiate?
Adult stem cells can only differentiate into a few types of cells while embryonic stem cells can in develop into almost any type of human cell
55
What is a way of collecting embryonic stem cells?
Using leftover embryos created for couples having fertility treatment
56
Why is the use of embryonic stem cells controversial?
When embryonic stem cells are extracted the embryo is killed
57
What is a bone marrow transplant used for?
Treating leukaemia
58
What happens during a bone marrow transplant?
The patient's white blood cells are destroyed and adult stem cells from someone else are put into the patient. These stem cells then multiply and produce new healthy white blood cells
59
Why can a bone marrow transplant not work?
The body can reject the cells and destroy them if they are too different
60
How does cloning help solve the problem of the body rejecting foreign cells from a bone marrow transplant?
If you make a cloned embryo of the patient you can use the embryonic stem cells to make white blood cells. These won't be rejected because the body will recognise them as their own cells
61
Why can a treatment with stem cells be dangerous?
The stem cells may produce the wrong kind of cell or create cancer cells
62
What forms genetic code?
The order of bases on a DNA strand
63
What are the names of the four bases found in DNA?
Adenine, cytosine, guanine and thymine
64
How many different amino acids are there in human proteins?
20
65
What do chains of amino acids form?
Proteins
66
What is protein synthesis?
The process of using the sequence of bases in DNA to form amino acids which build chains to form proteins
67
What two processes are used when making a protein?
Transcription and translation
68
Where does transcription take place?
Inside the nucleus
69
What is messenger RNA (mRNA)?
A strand of bases that are complementary to the original DNA strand
70
What is transcription?
The process of the DNA in a gene unzipping and mRNA being created based on a strand
71
How does the DNA in a strand unzip?
Weak hydrogen bonds between bases are broken
72
What is the difference between RNA and DNA?
RNA:
- only has one strand instead of two
- has a base called uracil instead of thymine
- is small enough to move out of the nucleus into the cell's cytoplasm
73
What does the ribosome do?
It moves from one end of the mRNA strand to the other decoding the bases in groups of three
74
What is another name for a base triplet?
A codon
75
What does transfer RNA (tRNA) do?
It brings complementary bases to line up with the codon, and releases an amino acid to join the chain
76
What happens when the ribosome decodes the whole mRNA strand?
A chain of amino acids is formed
77
What is a polypeptide?
A chain of amino acids
78
What do polypeptides do to form a protein?
They fold, twist and may link up with other polypeptides
79
What is a mutation?
A change in the sequence of bases in the genetic code
80
What part of the cell are organelles found in?
The cytoplasm
81
What is the complementary base of adenine?
Thymine
82
What is the complementary base of cytosine?
Guanine
83
What holds complementary base pairs together?
Weak hydrogen bonds
84
What is a genome?
All of the genes found in an individual
85
What did the Human Genome Project find out?
The order of 3 million base pairs that make up the human genome
86
What could the discovery of the human genome be used to develop?
- improved testing for genetic disorders
- new ways of finding genes that increase the risk of certain diseases
- new treatments and cures for disorders
- seeing how humans have evolved
- personalised medicines
87
What type of cells are gametes?
Haploid
88
When is meiosis used?
During reproduction
89
What are the drawbacks of cloning mammals?
Very few develop successfully
90
How many bases are there in a codon?
Three
91
What causes the shape of an enzyme?
It's amino acid sequence
91
What is a catalyst?
A substance that speeds up the rate of a reaction without being used up itself
91
What is an enzyme?
A biological catalyst
92
What is digestion?
The breaking down of larger molecules into smaller ones
93
What is synthesis?
The joining of smaller molecules to make larger ones
94
What are substrate molecules?
The molecules that enzymes work on
95
What happens when temperature is above or below the optimum temperature of an enzyme?
The rate of reaction slows down
96
What affects the rate of reaction of an enzyme?
- temperature
- pH
- substrate concentration
97
What does it mean when an enzyme is highly specific for a substrate?
It only works for that one substrate
98
What do carbohydrases break down?
Carbohydrates
99
What do proteases break down?
Proteins
100
What is the active site of an enzyme?
The place on an enzyme that has a special shape in order to hold the substrate molecule during a reaction
101
What is the lock-and-key hypothesis?
A hypothesis that says that enzymes only work when a certain substrate fits perfectly into the active site
102
What affects the shape of an active site of an enzyme?
Temperature and pH
103
What happens to an enzyme when temperature or pH are too extreme?
The enzyme denatures and the active site is destroyed
104
What is denaturation?
A change in the characteristics of a protein through heat, acidity or other factors that don't allow it to do its job
105
What are amino acids used to make?
Proteins
