1
Q
What is DNA?
A
2 strands stuck together to form a double helix
- (double stranded spiral)
2
Q
How many different sections is DNA separated into?
A
Separated into 46 different sections
3
Q
What is each section in DNA?
A
A really tight coil
—> forms a chromosome
4
Q
How many chromosomes does each cell have?
A
46
- 23 different types (2x each type)
5
Q
What are the 23rd pair of chromosomes in DNA?
A
Sex chromosomes
6
Q
What are the 2 sex chromosomes?
A
X and Y
7
Q
What is the sex chromosome for women?
A
XX
8
Q
What is the sex chromosome for men?
A
XY
9
Q
What is a gene?
A
Small section of a molecule of DNA that codes for a specific protein
—> small segment of a chromosome
10
Q
How many different types of amino acids are there?
A
20
11
Q
What does DNA determine about cell production?
A
Which proteins the cell produces
—> determines what type of cell it will be
12
Q
What would a red blood cell need loads of?
A
The protein haemoglobin
13
Q
What is a genome?
A
The entire set of genetic material (DNA) in an organism
14
Q
What would you have if you had an identical twin?
A
The same genome
15
Q
What can we do if we know the entire code that our DNA holds (complete human genome)?
A
Allows us to identify genes that are linked to certain types of diseases
16
Q
What do you inherit?
A
Genes
17
Q
What is an inherited disease?
A
The genes may cause a particular disease
18
Q
What might genes do?
A
Just increase the risk of a certain disease
19
Q
What do the genes we inherit do?
A
Determine the characteristics that we develop
20
Q
How many genes can a characteristic be determined by?
A
Usually several different genes that interact with each other
21
Q
What are there multiple forms of?
A
The same protein
22
Q
What does multiple forms of the same protein mean?
A
A different genetic code for each of those forms
- different codes are alleles
23
Q
What is an allele?
A
Different versions of the same gene
24
Q
How many copies do we have of every gene?
A
2
- 1 from each parent
25
What does having 2 copies of every gene mean?
We’ll have 2 alleles of each gene
- could be the same allele (homozygous)
- could be 2 different alleles (heterozygous)
26
What does heterozygous mean?
The 2 alleles are different in the genotype
27
What does homozygous mean?
Both alleles are the same for a genotype
28
What will each of the alleles be?
One allele will be dominant (always expressed)
One allele will be recessive
29
What does dominant allele mean?
Allele that is expressed in the phenotype even if only one copy is present
30
What does recessive allele mean?
Allele that is only expressed in the phenotype if two copies are present
31
What is a genotype?
The entire collection of alleles we have
The two alleles present for a particular gene
32
What do different alleles mean?
Different genotypes
- because they have different genetic codes
33
What is a phenotype?
Physical or resulting characteristics you get from your genotype
34
What does an upper case letter mean?
Dominant allele
35
What does a lower case letter mean?
Recessive allele
36
AA = ?
Homozygous
37
Bb = ?
Heterozygous
38
cc = ?
Homozygous
39
What are the 3 stages of the life cycle of a cell?
1) growth
2) DNA replication + mitosis
3) division (cytokinesis)
40
What is another name for division?
Cytokinesis
41
What happens to the cell during growth?
Cell grows in size
Increase in number of sub-cellular structures
- mitochondria, ribosomes
42
What happens to the cell during DNA replication + mitosis?
DNA is duplicated
- so the 2 new cells each have a full set of DNA
43
What is the DNA like when a cell isn’t dividing?
In long strings
44
What is the DNA like when a cell prepares for division?
DNA condenses into chromosomes
45
What happens as the cell continues to prepare for division?
It duplicates each of the 46 chromosomes
- duplicate stays attached to the o.g chromosome
46
What do the chromosomes do when the cell is ready to divide?
All 46 line up along the centre of the cell
- fibres from either side of the cell attach to their respective half of each chromosome
47
What do the cell fibres do to the chromosomes?
They pull the arms of the chromosomes to opposite sides of the cell
- o.g DNA at one side
- replicated DNA at the other
48
What are the 2 sides of the cell called?
Poles
49
What happens in the 3rd stage of the life cycle of a cell (division)?
Nuclear membrane forms around each set of chromosomes
Cell membrane + cytoplasm pull apart
- cytoplasm divides
50
What happens when the cell splits into 2?
Forms 2 daughter cells
- each cell has the same DNA
- 2 cells are identical + identical to o.g parent cell
51
What can the 2 daughter cells contribute to?
Growth
Development
Repair
Start cell cycle again
52
What are the stages of meiosis?
1) replicate DNA
2) chromosomes line up along centre of cell
3) 1st division
4) 2nd division
53
What happens during DNA replication (meiosis)?
Replication of chromsomes
- adds extra arm
54
When the chromosomes line up along centre of cell how are they arranged?
Left & right is random
55
What happens during the 1st division (meiosis)?
Chromosome pairs are pulled apart + cell splits in 2
Chromosomes are randomly distributed
- each half of cell get different combo of maternal + paternal chromosomes
—> DNA in each cell will be different
56
What happens during the 2nd division (meiosis)?
Chromosomes line up along centre of cell again
- but its the 2 arms of each chromosome that are pulled to opposite sides of the cell
When cell is ready, they’ll both divide in half again
- leaving us w 4 cells (gametes)
- 23 chromosomes in each
57
What are all 4 cells at the end of the 2nd division (meiosis)?
Genetically unique
58
Gametes - human process
Sperm + egg fertilisation
- diploid cell
- mitosis
- embryo
- fetus
- fully grown organism
59
What 2 factors can lead to huge variation between different individuals?
Differences in genes + our environment
60
What can differences in our genes + our environment lead to overtime?
Evolution of new species
- by process called natural selection
61
What does everyone have apart from identical twins?
A unique genome
- diff combos of proteins inside them
- why everyone looks diff
62
How can the environment affect identical twins (example, tall gene)?
Might have same genes for being tall
- if one didn’t eat or sleep as much as other, they might not be as tall
63
What are most of our characteristics determined by?
The interaction of our genes + our environment
64
Why are there many different genes?
Bc of mutations
65
What is a mutation?
A change in the DNA code
66
What can a mutation result in?
A different protein being produced + change a characteristic
67
Do most mutations have an affect on the proteins?
No
- don’t change the organism’s phenotype at all
68
What happens when the mutations do change the proteins?
The phenotype may change slightly
69
When the mutation does change the protein, which changes the phenotype, is it bad?
Usually bad + unwanted
V occasionally mutations are beneficial
70
Examples of mutations being beneficial
More resistant to lung disease
Ability to run faster
71
Can mutations be inherited?
Yes
72
What do the beneficial mutations mean?
Individuals who have them are more likely to survive
73
If the beneficial mutations mean you are more likely to survive what else does it mean?
More likely to be able to reproduce + pass on the genes to next generation
74
Who noticed the idea that the fittest individuals are more likely to survive?
Charles Darwin (in 1800s)
75
What did Charles Darwin call the idea that the fittest individuals are more likely to survive?
Survival of the fittest
76
What did Charles Darwin not know about but noticed?
Didn’t know abt mutations or genes
Did notice that certain traits were being passed on from parent to child
77
Which traits were being passed on from parent to child?
The most useful traits were passed on the most
- called this natural selection
78
What is natural selection?
The fittest individuals were being selected to survive
79
What is evolution?
Inheritance of certain characteristics in a population, over multiple generations, could lead to changes in the whole species
- or sometimes development of an entirely new species
80
What does evolution mean about all current species?
They must’ve evolved from different species sometime in the past
81
What does the theory of evolution by natural selection imply?
All living species must’ve evolved from the simple life forms that first developed more than 3 billion years ago
82
How has the theory of evolution by natural selection been proved?
Development of antibiotic resistance in bacteria (see evolution taking place)
Looking at fossil records
83
What are antibiotics?
Group of drugs that can kill bacteria
84
What is the most well known antibiotic?
Penicillin - 1st one discovered
85
What is a bad thing about penicillin (been using it for so long)?
Some types of bacteria have become resistant to it
86
How do bacteria become resistant to antibiotics (story)?
You have a colony of bacteria in you, giving you sore throat + headache
Doctors give you antibiotics
- in hope that they’ll the b
However, like all organisms, b can sometimes develop random mutations in their DNA
- change their characteristics
—> v occasionally these changes result in b being less affected by ab
Ab will kill most b but resistant one survives
B able to replicate quickly - new colony formed
- all have gene for ab resistance
Ab ur using isn’t affective anymore
- still infected + can pass ab resistant b onto other people
- then they can’t use that ab cos it won’t work + will have to get other ab
But some b could develop resistance to type of ab too + grow into a new colony
87
What is the new type of resistant bacteria called?
An antibiotic resistance strain
88
What are the bacteria’s resistant to loads of types of ab called?
Superbugs
E.g. MRSA
89
What does resistance do to the bacteria?
Makes it hard to kill
90
Is it common for bacteria to develop resistance?
It’s uncommon
91
When the bacteria do develop resistance what is it usually?
Only partial resistance
92
Why is it important to complete the full course of antibiotics?
So that we can kill all of bacteria
93
Describe a series of events that might result in zebras evolving to run more quickly
Variation among zebra production
- some can run faster than others
Mutation arises allowing some to run faster
Those z’s are more likely to survive
- therefore more likely to reproduce + pass on advantageous alleles
- repeats over multiple gens
—> advantageous allele spreads throughout population, until species has ‘evolved’ to run faster than
94
To reduce the rise + spread of ab resistance, what should we do?
Decrease use of antibiotics
95
What are 3 reasons why ab resistance is becoming more common?
Doctors often prescribe ab in cases where they aren’t necessary
- e.g. mild of viral infections
Many ppl don’t take full course of ab, not all b are killed
Huge amounts of ab are given to farm animals in order to make them grow faster + prevent them from getting ill in the 1st place
96
Why is the spread of ab resistance a problem?
If more b are resistant to ab, we won’t be able to treat those infections
- means more ppl will die of bacterial infections
97
What does evolution occur through?
The natural selection of certain genetic changes that give rise to the phenotypes that are best suited to the environment
- given enough time phenotypes of 2 different populations within a species may become so different that they can no longer interbreed to produce fertile offspring
—> say that a new species has been formed
98
What is the problem with using many antibiotics?
Resistance is bound to arise
99
Why are we using so many antibiotics?
Doctors often prescribe ab’s in cases where it is not necessary
- e.g. mild or viral infections
100
What is the biggest problem with antibiotics?
Farming
101
Why is farming a big problem for antibiotic resistance?
Over 2/3 of 100,000 tonnes of ab is given to animals
- farmers put ab in food of healthy animals
—> to prevent them from getting ill + make them grow faster
—> basically a breeding ground for ab resistance
102
Where are genes located?
On the chromosomes (which is in the nucleus of cell)
103
What does mitosis occur during?
Growth
Repair
Cloning
Asexual reproduction
104
How does random fertilisation produce genetic variation of offspring
Fertilisation is random
Any sperm can fertilise any egg
Sperm/eggs are genetically different
Creates unique combination of alleles
Offspring are genetically different
Biology
flashcards
Decks in class (16)
# Cards
-
Nature And Variety Of Organisms Yr953
-
Movement Of Substances Yr927
-
Human Nutrition Yr974
-
Plant Nutrition And Transport Yr1041
-
Respiration And Gas Exchange Yr 1029
-
Blood And Organs Yr1032
-
Coordination & Response Yr1068
-
Respiration And Gas Exchange Yr1056
-
Gas Exchange And Transport In Plants Yr1055
-
Transport In Humans Yr10109
-
Coordination And Response Yr10119
-
Reproduction Yr10117
-
Ecology And The Environment Yr1168
-
Inheritance Yr11104
-
Biological Resources Yr1175
-
Reproduction Yr1039
