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Higher Biology > Unit 1- DNA and The Genome > Flashcards

Unit 1- DNA and The Genome Flashcards

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1
Q

Strcuture of DNA

A
  • DNA is a double-helix consisting of repeating units of DNA nucleotides
  • In the double helix the two DNA strand are anti parallel, one strand runs in the 5’ to 3’ direction and the other runs in the 3’ to 5’ creating a double strabded helix
  • There is a Deoxyribose sugar at the 3’ end and a Phosphate group at the 5’ end
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2
Q

Structure of a nucliotide

A

A DNA nucleotide consists of 3 components:
Deoxyribose sugar
Organic Base [A,T,C,G]
Phosphate group

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3
Q

How is the phosphate back bone created in DNA

A
  • The DNA nucleotides in a strand of DNA are joined together by strong chemical
    bonds     between the phosphate group of one nucleotide and the** deoxyribose sugar **of another nucleotide

*Hydrogen binds

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4
Q

Orginisation of DNA in eukaryotes

A
  • ** LINEAR CHROMOSOMES** in the nucleus of EUKARYOYES
  • plant, animal & fungal cells
  • Yeast is a eukaryote but has a plasmid
  • Cirular chromosome found in mitochondria and chloroplast of eukaryote
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5
Q

orginisation of DNA in prokaryotes

A
  • CIRCULAR CHROMOSOMES in the cytoplasm of PROKARYOTES
    Bacteria
  • Have plasmid
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6
Q

What is DNA tightly coiled around creating a chromosome

A

DNA is tightly coiled & packaged with associated Histone Proteins.

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7
Q

When does DNA replication happen

A

prior to cell division

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8
Q

What are primers

A
  • Primers allow DNA polymerase to start repilication
  • They can only bind to the 3’ of thr template strand
  • They are a short strand of nucleiotides
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9
Q

DNA replication step 1

A

DNA strand unnwinds, breaking hydrogenbonds and creating two template strands

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10
Q

DNA replication step 2

A

Primer attaches to 3’ of each strand. Therefore DNA polymerase can add free complementry nucleotides to each strand.

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11
Q

DNA Replication step 3

A

since primers add only in the 3’ direction this creates** fragments **in the lagging strand
Enzyme Ligase joins these fragments togeyher

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12
Q

PCR

polymerase chain reaction

A
  • PCR AMPLIFIES DNA using complimentary primers for specific target sequences
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13
Q

PCR step 1

A

DNA is heated to between 92-98 degress to seperate the strands

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14
Q

PCR step 2

A

DNA is then cooled to between 50-65 dgerees to allow specific target sequenceto bind

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15
Q

PCR step 3

A

DNA is heated to between 70-80 degrees to allow specific HEAT TOLLERENT DNA PLOYMERASE to replicate the region of DNA

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16
Q

What is gene expression

A

Cellular Differentiation is the process by which a cell expresses certain genes to produce PROTEINS characteristic for that type of cell. This allows a cell to carry out specialised functions.

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17
Q

STEM cells

A

Stem cells are UNSPECIALISED CELLS in animals that can divide (SELF-RENEW) and/or Differentiate.

There are 2 Types of Stem Cells : Embryonic and Tissue

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18
Q

Embryonic stem cells

A

Embryonic stem cells can differentiate into all cell types that make an orginism

THIS MEANS THEY ARE PLURIPOTENT

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19
Q

Tissue stem cells

A

TISSUE stem cells are involved in the GROWTH, REPAIR and RENEWAL of the cells found in that tissue.

They can differnetiate into all cells of their particular tisssue. Making them multipotent

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20
Q

THERAPEUTIC AND RESEARCH USES OF STEM CELLS

A

Theraputic
* repair of damaged or diseased organs or
tissues.
* Stem cells can be used to repair damaged CORNEA in the eye.

Research
* They’re used as model cells to study how diseases develop

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21
Q

Meristem

A
  • Meristems are regions of unspecialised cells in plants that can divide (self-renew) and/or differentiate.
  • Apical meristems are found in the **Root Tip & Shoot Tip. **These give rise to increase in length/height.
  • Lateral meristems, also known as Cambium, are found in vascular bundles between the Xylem & Phloem. These give rise to Thickening of the plant.
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22
Q

What is the genome

A

The Genome of an organism is it’s entire hereditary information encoded in DNA.

A genome is made up of GENES and other DNA sequences that do not code for proteins

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23
Q

Whats a gene

A

DNA sequences that code for protein are defined as GENES.
These sequences are transcribed to produce the Primary mRNA transcript during protein synthesis.

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24
Q

What do non-coding sequences do

A
  • Regulate transcription
  • transcribed but never translated. E.g tRNA and rRNA are non-translated forms of
    RNA.
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25
26
What is Gene Expression?
Gene Expression involves the transcription and translation of DNA sequences.
27
Are all genes in a cell expressed?
Only a fraction of the genes in a cell are expressed.
28
What types of RNA are involved in transcription and translation?
Transcription and translation involves 3 types of RNA: mRNA, tRNA and rRNA.
29
What is the structure of RNA?
RNA is single stranded and is composed of nucleotides containing Ribose sugar, phosphate and 1 of 4 bases: Cytosine, Guanine, Adenine and Uracil.
30
What replaces Thymine in RNA?
Uracil replaces Thymine in RNA.
31
What is the function of Messenger RNA (mRNA)?
Messenger RNA (mRNA) carries a copy of the DNA code from the nucleus to the Ribosome.
32
What is a CODON?
Each triplet of bases on the mRNA molecule is called a CODON and codes for a specific amino acid.
33
What role does tRNA play in protein synthesis?
tRNA folds due to complementary base pairing and carries its specific amino acid to the ribosome.
34
What is found at one end of a tRNA molecule?
A tRNA molecule has an anticodon (an exposed triplet of bases) at one end.
35
What is at the other end of a tRNA molecule?
An attachment site for a specific amino acid is at the other end of a tRNA molecule.
36
What is the role of Ribosomal RNA (rRNA)?
Ribosomal RNA (rRNA) and Proteins are used to form the Ribosome.
37
What does RNA Polymerase do?
RNA Polymerase moves along DNA unwinding the double helix and breaking the hydrogen bonds between the bases.
38
What does RNA Polymerase synthesize?
RNA Polymerase synthesizes a primary mRNA transcript from RNA nucleotides by complimentary base pairing.
39
What are introns?
Introns are non-coding regions of DNA that do not contain the information required to produce a protein.
40
What is RNA splicing?
RNA splicing is the process of removing non-coding introns and joining together the coding regions known as exons.
41
What are exons?
Exons are the coding regions of DNA that contain the information required to produce a protein.
42
What happens to the order of exons during splicing?
The order of exons remains unchanged during splicing.
43
What is the clue to remember the relationship between introns and exons?
The clue is NICE (Non-coding Introns, Coding Exons).
44
What is Alternative RNA Splicing?
Different proteins can be expressed from one gene as a result of Alternative RNA Splicing. Different mature mRNA transcripts are produced from the same primary transcript depending on which exons are retained.
45
What role does tRNA play in translation?
tRNA is involved in the translation of mRNA into a polypeptide at a ribosome.
46
When does translation begin and end?
Translation begins at a START CODON and ends at a STOP CODON.
47
How do anticodons interact with codons?
Anticodons bond to codons by complementary base pairing, translating the genetic code into a sequence of amino acids.
48
What joins amino acids together during translation?
Peptide bonds join the amino acids together.
49
What happens to tRNA after amino acids are joined?
Each tRNA then leaves the ribosome as the polypeptide is formed.
50
What are amino acids linked by?
Amino acids are linked by peptide bonds to form polypeptides.
51
How do amino acids become joined together?
Amino acids become joined together by peptide bonds in a particular genetically-determined sequence.
52
What do polypeptide chains fold to form?
Polypeptide chains fold to form the 3-dimensional shape of a protein.
53
What holds the 3-dimensional shape of a protein together?
The shape of a protein is held together by hydrogen bonds and other interactions between individual amino acids.
54
What determines the functions of proteins?
Proteins have a large variety of shapes which determines their functions.
55
What determines phenotype?
Phenotype is determined by the proteins produced as the result of gene expression.
56
What influences phenotype besides gene expression?
Environmental factors also influence phenotype.
57
What are mutations?
Mutations are changes in the DNA that can result in no protein or an altered protein being synthesised.
58
What is a Single Gene mutation?
A Single Gene mutation involves the alteration of a DNA nucleotide sequence as a result of substitution, insertion, or deletion of nucleotides.
59
What are the types of alterations in Single Gene mutations?
The types of alterations are substitution, insertion, and deletion.
60
What are substitution mutations?
Substitution mutations involve one DNA nucleotide being swapped/substituted for another.
61
What are examples of substitution mutations?
Missense, Nonsense, and Splice-site mutations are all examples of substitution mutations.
62
What is a missense mutation?
Missense mutations result in one amino acid being changed for another, which may result in a non-functional protein or have little effect on the protein.
63
What do nonsense mutations result in?
Nonsense mutations result in a premature STOP CODON being produced.
64
What is the consequence of a premature STOP CODON?
It results in the termination of protein synthesis.
65
What are splice-site mutations?
Mutations that affect the splicing of pre-mRNA, leading to changes in the mature mRNA transcript.
66
What is the effect of splice-site mutations on introns?
Some introns may be retained in the mature mRNA transcript.
67
What is the effect of splice-site mutations on exons?
Some exons may not be included in the mature mRNA transcript.
68
What are Insertion Mutations?
Insertion Mutations involve an extra DNA nucleotide being added/inserted into the DNA sequence.
69
What are Deletion Mutations?
Deletion Mutations involve a DNA nucleotide being left out/deleted from the DNA sequence.
70
What is the result of both Insertion and Deletion mutations?
Both Insertion and Deletion mutations result in a Frame-shift.
71
What do Frame-shift mutations cause?
Frame-shift mutations cause ALL of the codons and all of the amino acids after the mutations to be changed. ## Footnote This has a major effect on the structure of the protein produced.
72
What is a chromosome mutation?
A chromosome mutation involves a change in the structure or number of chromosomes.
73
What are the four types of chromosome mutations? TIDD
The four types of chromosome mutations are Deletion, Inversion, Translocation, and Duplication.
74
What is deletion in chromosome mutations?
Deletion is where a section of a chromosome is removed. ## Footnote Example: ABCDE FGH becomes ABCEFGH (Gene D has been deleted).
75
What is inversion in chromosome mutations?
Inversion is where a section of a chromosome is reversed.
76
What is translocation in chromosome mutations?
Translocation is where a section of a chromosome is added to a different chromosome, not its homologous partner.
77
What is the potential impact of chromosome mutations?
The substantial changes in chromosome mutations often make them lethal.
78
What is duplication in genetics?
Duplication is where a section of a chromosome is added from its homologous partner.
79
Can duplications be beneficial or detrimental?
Some duplications can be highly detrimental whilst others can be important in evolution.
80
How does duplication contribute to evolution?
Duplication allows potential beneficial mutations to occur in a duplicated gene while the original gene can still be expressed to produce its protein.

Higher Biology (3 decks)

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