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SFN 316 Forensic Molecular Biology > Chapter 2 > Flashcards

Chapter 2 Flashcards

(75 cards)

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1
Q

Webster’s Definition of DNA

A

An essential of all living matter and a basic material in the chromosomes of the cell nucleus: it contains the genetic code and transmits the hereditary pattern

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2
Q

Purpose of DNA

A
  1. Make copies of itself so cells can divide and carry the same information
  2. Carry instructions on how to make proteins
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3
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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4
Q

Where is DNA found?

A

Almost every cell of the body

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5
Q

DNA’s “Alphabet”

A

DNA is made up of four nucleotides, represented by 4 letters: A, T, G, C

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6
Q

What is the important of the letters in DNA?

A

The order of the letters is what makes everyone different

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7
Q

How similar is human DNA?

A

Over 99% of human DNA is the same from person-to-person

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8
Q

How is nuclear DNA inherited?

A

Half of the nuclear comes from the mother and half comes from the father

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9
Q

True or False: An individual’s DNA profile remains the same throughout life

A

True

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10
Q

True or False: Each person’s DNA is the same in every cell

A

True

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11
Q

What are nucleic acids composed of?

A

Long chains of repeating units called nucleotides

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12
Q

What are the three components of nucleotides?

A
  1. Sugar
  2. Nitrogen-containing heterocyclic base
  3. Phosphoric acid unit
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13
Q

What is the sugar in RNA?

A

Ribose

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14
Q

What is the sugar in DNA?

A

Deoxyribose

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15
Q

What is the difference between ribose and deoxyribose?

A

In ribose, there is an H attached to the 2’ position of the ring
In deoxyribose, it is an OH group

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16
Q

Nitrogenous bases

A

Form a bond with carbon 1 of the pentose ring

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17
Q

Purines

A

Double-ringed bases
Adenine and Guanine

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18
Q

Pyrimidines

A

Single-ring bases
Cytosine, Thymine (DNA only), and Uracil (RNA only)

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19
Q

What is the primary structure of DNA?

A

The sequence of bases in a strand of DNA
(e.g. AATTTGGCTTAA)

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20
Q

What is the secondary structure of DNA?

A

The double helix: each DNA molecule has two polypeptide chains wound around each other like a spiral structure

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21
Q

Ladder Analogy for Secondary Structure of DNA

A

The phosphate-sugar backbone represents the handrails
Pairs of bases linked together by hydrogen bonds represent the steps

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22
Q

What does DNA being anti-parallel mean?

A

The strands of the double helix are organized in opposite orientation, so that the 5’ end of one strand is aligned with 3’ end of the other strand

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23
Q

Chromatin

A

The complex of DNA and proteins in the nucleus of the interphase cell

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24
Q

Can individual chromosomes be distinguished in chromatin?

A

No

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25
Nucleosomes
The basic subunit of chromatin
26
What are nucleosomes composed of?
200 base pairs and an octane of histone proteins
27
Histones
Conserved DNA-binding proteins of eukaryotes that form the nucleosome
28
Genes
Segments of DNA molecules that control the production of different proteins in an organism
29
How do genes vary?
Vary in terms of the number and sequence of base pairs they contain
30
What do genes consist of?
Exons and introns
31
Exons
Segment of a gene that is represented in the final mRNA product
32
Introns
Non-coding DNA which separates neighboring exons in a gene
33
How are genes also described?
As the basic units of heredity
34
Genome
All the genetic material in the chromosomes of a particular organism
35
How are exons expressed?
As proteins
36
What does the Central Dogma define?
The paradigm of molecular biology: genes are perpetuated as sequences of nucleic acid, but function by being expressed in the form of proteins
37
How is genetic information perpetuated?
By replication
38
Replication
Double stranded DNA is duplicated to give identical copies
39
What happens after DNA is duplicated in replication?
One of the copies is transmitted to one daughter cell and one to the other
40
What happens before a cell divides during replication?
The double helix strand starts to unwind
41
What does each unwinding DNA strand serve to do?
They serve as a template for the formation of a new complementary strand
42
What the nucleotides attracted to?
Exposed bases and they become hydrogen-bonded to them
43
What is complementary base pairing?
A and T are complementary and only bind to each other C and G are complementary and only bind to each other
44
Codon
A sequence of three nucleotides in mRNA
45
Steps of Transcription
1. RNA polymerase binds to specific sequence of DNA known as the promoter 2. The enzyme unwinds a small segment of the double helix, which exposes the bases of the two single strands 3. As the polymerase moves along the DNA, complementary ribonucleotides are added to the chain 4. Generates a single-stranded RNA identical in sequence with one of the stands of the duplex DNA
46
What does transcription generate?
A single-stranded RNA identical in sequence with one of the stands of the duplex DNA
47
What do codons code for?
An amino acid
48
Where does translation occur?
Ribosomes
49
Anticodon
A nucleotide triplet at the end of the tRNA
50
What is an anticodon complementary to?
An mRNA codon
51
Translation
A specific amino acid is bound to the opposite end of tRNA Converts the nucleotide sequence of the mRNA into the sequence of amino acids comprising a protein
52
Hybridization
The binding or reassociation of complementary strands of nucleic acid or oligonucleotides
53
Oligonucleotides
Short RNA or DNA molecules, single stranded, typically synthesized in a laboratory
54
Locus
Chromosomal positon or location of gene or sequence of DNA; plural is loci
55
DNA Marker Nomenclature
D16S539 D: DNA 16: Chromosome 16 S: Single copy sequence 539: 539th locus described on chromosome 16
56
Homologous chromosomes
1. Same size 2. Contain the same genetic structure
57
Alleles
An alternative of a gene or section of DNA at a locus
58
What are the two primary forms of DNA variation?
1. Sequence polymorphism 2. Length polymorphism
59
Sequence polymorphism
One or more nucleotides vary within a particular DNA sequence or length of DNA
60
Length polymorphism
Sequence of DNA doesn't vary, but the number of times that the sequence is repeated varies
61
Power of discrimination
Ability of a forensic DNA technique to discern the difference between individuals
62
Genetics
Study of patterns of inheritance of specific traits between parents and offspring
63
What does much a genetics involve in modern day?
Populations
64
Populations
Groups of individuals residing in a given area at a given time
65
How are populations often classified?
By grouping together those sharing a common ancestry
66
Population genetics
Study of genetic diversity in populations and how it changes through time
67
What are the laws of Mendelian Genetics?
1. Law of segregation 2. Law of Independent assortment
68
Law of Segregation
Chromosome pairs separate during meiosis so that the sex cells (gametes) become haploid and possess only a single copy of a chromosome An individual can receive only one allele of a particular gene from one parent
69
Law of Independent Assortment
Different segregating gene pairs behave independently due to recombination where genetic material is shuffled between generations
70
Recombination
The process of exchanging DNA between homologous chromosomes that can occur during meiosis through crossing over
71
What does recombination generate?
New combinations of allies or genes, and a shuffling of genetic material
72
Linkage
Proximity of two or more markers on a chromosome
73
What does it mean when genetic markers are closer together?
The lower the probability that they will separate and the greater the probability that they will be inherited together
74
Linkage equilibrium
The condition among alleles at different loci such that any allelic combination in a gamete occurs as the product of the frequencies of each allele at its own locus
75
Linkage disequilibrium
The condition among alleles at different loci such that any allelic combination in a gamete do not occur according to the product rule of probability

SFN 316 Forensic Molecular Biology (4 decks)

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