Week 1 Flashcards

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1
Q

What are changes in DNA sequences linked to?

A

Phenotypic variation

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2
Q

DNA Strands orientation

A

Phosphodiester bonds link the 5’ phosphate group of one nucleotide to the 3’ hydroxyl group of another nucleotide
- Strands have polarity
- Run antiparallel
- Have complementary base pairs

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3
Q

Def: Covalent Bond

A

Type of chemical bond where two atoms are connected to each other by the sharing of two or more electrons

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4
Q

Nucleotides

A

DEOXYRIBOSE SUGAR
- 5 carbon sugar
NITROGENOUS BASE ( A,C,T,G)
- attached to deoxyribose sugar at 1’ carbon by covalent bond
PHOSPHODIESTER BOND
- 5’ carbon with phosphate group and the 3’ carbon of the next nucleotide

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5
Q

Types of nitrogenous bases

A

PYRIMIDINES
- Cytosine and Thymidine
- One ring
PURINES
- Adenosine and Guanine
- 2 ring structure, larger
Form hydrogen bonds with different DNA strands

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6
Q

Def: Hydrogen bonds

A

Noncovalent bonds that form between partial charges that are associated with hydrogen, oxygen and nitrogen atoms of nucleotide bases

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7
Q

Why are DNA stands antiparallel?

A

5’ to 3’ polarity of the phosphodiester bonds is in the opposite orientation

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8
Q

Chargaff’s Rule

A

Percentages of adenine and thymine are approximately equal and the same for cytosine and guanine
- Bond with each other

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9
Q

How is DNA semiconservative?

A

Two complementary strands separate and each acts as a template for the synthesis of a new complementary strand
- Daughter cell contains one new and 1 original strand

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10
Q

Central Dogma of Molecular Biology

A

INFORMATION FLOW IN BIOLOGICAL SYSTEMS
DNA to RNA: RNA transcription
RNA to DNA: Reverse transcription
DNA to DNA: DNA replication
RNA to RNA: RNA replication (viruses)
RNA to Protein: Protein translation
Pro to Pro: Prions, inteins, and posttranslational modification
Protein to DNA: DNA methylation

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11
Q

Transcription

A
  • The use of one strand of DNA to direct synthesis of a single-stranded RNA
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12
Q

Fate of transcribed RNA

A
  • Some translated into protien
  • Other is not translated and has enzymatic or regulatory function as RNA - without encoding protein
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13
Q

Regulation of transcription

A

PROMOTOR REGION
- Promoters do not get transcribed
- Control the transcription of downstream regions
- In bacteria and archaea, one promotor can regulate transcription of multiple genes - typically not the case in eukaryotes, with some exceptions (ribosomal RNA)
EXONS AND INTRONS
- In eukaryotes, genes may have exons and introns
- Introns are removed before translation (splicing)
- In bacteria and archaea, there is only one exon (no splicing)
- Some exons contain UTRs (untranslated regions) - upstream and downstream buffer regions
- Exons may be completely or partially translated

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14
Q

Translation

A
  • mRNA to Polypeptide
  • Nucleotides have a non-overlapping, triplet codon that encodes the sequence of amino acids to proteins
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15
Q

Def: Monohybrid Cross

A

A cross between two individuals that are heterozygous at a gene that controls a phenotype of interest

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16
Q

Def: Test Cross

A

When an individual with a dominant phenotype is crossed with a homozygous recessive individual in order to determine whether the dominant phenotype is due to a homozygous or heterozygous genotype
- If the dominant phenotype is due to a heterozygous genotype, the phenotypic ratio of the test cross is 1:1

17
Q

Mendel’s Law of Segregation

A

The alleles of an individual separate during the formation of gametes
- Diploid individuals have two versions of each gene (Alleles) and each gamete contains only one of these alleles

18
Q

Def: Dihybrid Cross

A

A cross between parents that are heterozygous at two different genes that control two different phenotypes

19
Q

Def: Double Heterozygous

A

Generated by crossing two lines that are pure breeding for two traits

20
Q

Mendel’s Law of independent Assortment

A

The alleles of two (or more) different genes get sorted into gametes independently of one another

21
Q

What are the three major types of information carrying biopolymers

A

DNA, RNA, Protein

22
Q

What are the three major types of information exchange between information carrying biopolymers?

A

Replication - DNA to DNA
Transcription - DNA to RNA
Translation - RNA to protein

23
Q

Do all exons of protein coding genes encode protein?

A

No, some exons are entirely 5’ UTRs or 3’UTRs

24
Q

Are all enzymes made up of amino acids

A

No, there are also RNA enzymes

25
Q

Are promotors transcribed or translated?

A

Neither

26
Q

Are Exons Transcribed or translated?

A

Transcribed and sometimes translated

27
Q

Are Intros transcribed or translated?

A

Transcribed but not translated

28
Q

Are Poly-A transcribed or translated?

A

Neither

29
Q

Are UTRs transcribed or translated?

A

Transcribed but not translated

30
Q

What is meant by DNA being polar

A

DNA polarity refers to the way the ribose sugars within each strand of DNA are linked together from the 5’ C to the 3’ C

31
Q

What is meant by DNA being anti-parallel?

A

DNA being antiparallel refers to double stranded DNA having the polarity of one strand oriented in the opposite direction from the other strand

32
Q

What DNA component determines polarity

A

Deoxyribose sugar

33
Q

Which amino acid does the start codon encode?

A

Methionine

34
Q

Which amino acid does the stop codon encode?

A

None

35
Q

What is a phosphodiester bond?

A

A type of covalent bond that links 5’ phosphate group of one nucleotide to the 3’ hydroxyl group of another nucleotide

36
Q

Are Watson-Crick base pairs between two purines or two pyrimidines or between purine and pyrimidine

A

Between Purine and Pyrimidine
- C (a pyrimidine) pairs with G (a purine)
- T (pyrimidine) pairs with A (purine)

37
Q

What type of chemical bond is involved with base-pairs between different strands of DNA?

A

Hydrogen bonds - non covalent

38
Q

What is Chargaff’s Rule and what is the biological basis for this rule?

A

The percentage of A and T are about the same and the percentage of G and C are about the same because they are Watson-Crick base pairs in DNA