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Higher Biology > Unit 1 > Flashcards

Unit 1 Flashcards

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1
Q

What is a Deoxyribose sugar made of?

A

A Phosphate group and an organic base

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2
Q

4 bases

A

Adenine, Thymine, Guanine and Cytosine

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3
Q

What are the bases linked by?

A

Weak hydrogen bonds

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4
Q

Features of a Prokaryote

A

No true nucleus; Circular DNA, Few organelles

Bacterial cell

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5
Q

Features of a Eukaryote

A

True nucleus, double nuclear membrane, Linear DNA

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6
Q

What does a nuclear membrane do?

A

Separates the nucleus from the cytoplasm

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7
Q

For DNA replication to occur, what must the nucleus contain?

A

Primers, Bases, Enzymes and a supply of DNA

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8
Q

What catalyses DNA replication?

A

DNA Polymerase

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9
Q

2 strands of DNA replication?

A

Leading and Lagging strand

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10
Q

What is meant by Semi conservative replication?

A

Each DNA double helix has one original strand and one new strand

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11
Q

What is the importance of DNA?

A

DNA encodes the hereditary information in a chemical language; stored as a base sequence of DNA (the genome)

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12
Q

What is PCR?

A

A technique used to make many copies of a small sample or fragment of DNA in a lab.

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13
Q

What does the reaction mixture in PCR contain? (5)

A
  • Original DNA strand
  • DNA Polymerase
  • DNA nucleotides
  • Primers
  • ATP
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14
Q

What is the enzyme used in PCR?

A

Taq polymerase

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15
Q

What happens in the first step of PCR?

A

DNA is heated to a very high temperature to break the weak hydrogen bonds.

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16
Q

What happens in stage 2 of PCR?

A

It is cooled. At a lower temperature, the primers can then form hydrogen bonds.

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17
Q

What happens at stage 3 in PCR?

A

The temperature is increased to allow a special heat tolerant DNA polymerase can then add on nucleotides.

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18
Q

What are the uses of PCR?

A
  • Forensic: blood or tissues samples

- Paternity cases

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19
Q

What is the structure of RNA?

A
  • Ribose sugar, a phosphate group and a base (A,G,C or U)
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20
Q

What is mRNA?

A

Carries a copy of the genetic code to the Ribosomes

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21
Q

Where is tRNA found and what is it role?

A

Found in the cytoplasm

Carries a specific amino acid

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22
Q

What is rRNA?

A

rRNA and associated proteins together form a ribosome.

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23
Q

Stages of Gene expression (in order)

A 
Transcriptions
RNA Splicing 
Translation 
Folding - post translational modification
(~Protein is formed~)
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24
Q

What is Transcription?

A

Synthesis of mRNA from DNA, within the nucleus

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25
What enzyme is present during Transcription?
RNA Polymerase
26
What happens during RNA Splicing?
Introns are removed; Exons are 'spliced' together to form mature messenger RNA transcript.
27
What is Translation?
Synthesis of a protein from a specific amino acid using the code in mRNA at the ribosomes.
28
What is folding?
Hydrogen bonds and disulphide bridges hold the chains of amino acids in their 3D shape.
29
What is post-translational modification?
Cutting and combining different protein chains, adding phosphate to the protein.
30
What are Meristems?
Regions of unspecialised cells in plants capable of cell division.
31
Name the 2 different types of Meristems
Apical and Lateral
32
Where are Apical Meristems?
Found at the root and shoot tips, capable of elongating
33
Where are Lateral Meristems found?
Found in Cambium; in both root and stems
34
What are stem cells?
Unspecialised somatic cells
35
What are Embryonic stem cells?
Cells which are capable of differentiating into all cell types (pluripotent) found within a blastocyst.
36
What are Adult stem cells needed for?
For growth, repair and renewal of tissues of only limited cell types.
37
What are stem cells used for in research?
Model cells to study how diseases develop.
38
Therapeutic uses of stem cells
Repair of damaged or diseased organs or tissues | e.g. skin grafts for severe burns
39
Future potential of stem cells
provide treatment for diabetes, Alzheimer's disease and cardiac disease.
40
Function of non-coding sequences
No known function and to regulate transcription
41
What are the factors which increase the rate of mutations known as and give examples
Mutagenic agents - Chemical: mustard gas - Radiation: X-Rays
42
What are single gene mutations?
A change in one of the base pairs in a DNA sequence of a gene.
43
What are the 3 different types of single gene mutations?
- Insertion - Deletion - Substitution
44
What is insertion?
When an extra base is inserted into DNA. All amino acids after the insertion will be different (major changes) Known as a Frame-shift mutation
45
What is Deletion?
When a base is deleted in DNA; also known as a Frame-shift mutation.
46
What is Substitution?
When a base is replaced by a different base in DNA; only has a minor effect
47
What are the 3 types of Substitutions?
- Missense: results in a triplet that codes for a different amino acid - Non-sense: Results in a stop codon - Splice-site: a nucleotide is substituted at a site where introns are normally removed.
48
What are Chromosome structure mutations?
Changes to the number or sequence of genes in a chromosome.
49
What are the 4 different types of Chromosomal mutations?
- Duplication - Deletion - Translocation - Inversion
50
What is Duplication?
When a set of genes are repeated or duplicated on the chromosome.
51
What is Inversion?
When genes are rotated 180 degrees.
52
What is Translocation?
When a section of a chromosome breaks off from original chromosome and attaches itself to another chromosome.
53
What is important about mutations in Evolution?
Only source of new variation: gives an individual a survival advantage.
54
What is Meiosis?
When only one set of chromosomes are present in each cell: each gamete has a haploid number of chromosomes (n)
55
What is Non-disjunction?
When an error can occur through spindle fibre formation and the matching chromosome fails to separate.
56
What is complete non-disjunction?
When the spindle fibres fails altogether, which can result in a cell with a complete extra set of chromosomes.
57
What is Polyploidy?
If there is more than 2 complete sets of matching chromosomes in an organism. Common in plants but very rare in animals.
58
How can polyploidy benefit the production of plants?
- Greater yields - Larger cells and grow faster - Greater resistance to disease
59
What does evolution involve?
Inheritance, Selection, Drift and speciation
60
What is inheritance?
The passage of genetic information from parent to offspring
61
What are the 2 types of inheritance?
Vertical and Horizontal
62
What is horizontal inheritance?
When genetic material can pass across from one cell to another horizontally within the same generation or from one species to a different species of prokaryotes.
63
Why might many offspring die ?
due to the lack of food availability, over-crowding and the lack of resistance to disease
64
What is male to male competition?
When fight to gain the best breeding site or territory. They use "weapons" such as antlers or tusks
65
What is female choice?
The female "selects" or "chooses" the male to mate with. | Male is likely to have advantageous alleles.
66
What are the 3 ways that natural selection can affect a population?
- Stabilising - Directional - Disruptive
67
What does stabilising selection do?
Gives an advantage to individual that posses the average phenotype. (graph gets thinner, same mean)
68
What is directional selection?
Favours alleles at one phenotypic extreme, in response to a change in an environmental pressure. (Graph moves along the x-axis, new mean)
69
What is Disruptive selection?
Favours 2 extreme forms of a characteristic | the population splits into two distinct groups: each with its own means
70
What are Neutral mutations?
Affected by genetic drift and therefore may increase or decrease in frequency.
71
What is the founder effect?
A small group of organisms are isolated from the rest of population. Has a random selection of alleles.
72
What do isolation barriers do?
Prevent gene flow between populations, stopping the populations from interbreeding.
73
What are the 3 types of isolation?
Geographical, behavioural and ecological
74
What does geographical isolation lead to?
Allopatric Speciation
75
What does behavioural and ecological isolation lead to?
Sympatric Speciation
76
What is allopatric speciation?
When a geographical barrier separates two (or more) populations, such as mountain ranges, rivers, deserts and seas. This prevents gene flow.
77
What is sympatric speciation?
When gene flow between the populations is prevented by a behavioural or ecological barrier. Produces 2 species which don't interbreed
78
What is a behavioural barrier?
Changes in reproductive behaviour
79
What is an ecological barrier?
Changes in abiotic conditions
80
What is a Hybrid zone?
Gene flow between the sub-populations. | An area where two populations meet and interbreed to produce fertile, hybrid offspring.
81
What are Genomics?
Sequences of nucleotide bases in the entire genome; study of genomes
82
What is bioinformatics?
The comparison of gene sequences using computers and statistics.
83
What is used to work out a sequence of bases within a fragment of DNA?
Restriction endonuclease
84
What is Phylogenetics?
Study of 'evolutionary relatedness' among different groups of organisms, using phylogenetic trees.
85
What is evolutionary distance?
The number of differences per unit length of DNA between 2 genomes; the further apart the 2 species, the more distantly related they are.
86
What are molecular clocks used for?
To estimate the data of the origins of groups of living organisms and the sequence in which they evolved.
87
What are the 3 domains of life?
Bacteria - Prokaryotes Archaea Eukaryotes
88
What is combined evidence?
Data from genome sequences and fossil evidence has been used to produce a timeline of the key events in evolution.
89
What does the comparison of genomes do?
It shows many genes are highly conserved across different organisms.
90
What is personal genomics?
Sequencing of a person's entire genome (all the DNA bases) and its analysis.
91
What is a genetic disorders a result of?
A result of a variation in Genomic DNA sequences.
92
What is Personalised Medicine?
A study of how drugs work in the body (pharmacology); Analysing an individual' genome can lead to a greater understanding of the genetic components of the risks of particular diseases.
93
Name an advantage to Personalised medicine
- Increases the effectiveness of the drug and reduces any possible side effects.
94
Name a disadvantage to personalised medicine
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Higher Biology (4 decks)

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