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CHEMISTRY 60 > CHAPTER SEVENTEEN: NUCLEIC ACIDS AND PROTEIN SYNTHESIS > Flashcards

CHAPTER SEVENTEEN: NUCLEIC ACIDS AND PROTEIN SYNTHESIS Flashcards

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1
Q

What are the 2 closely related types of nucleic acids?

Both are _______ polymers of repeating ______ units known as ____________.

A

DNA and RNA

unbranched; monomer; nucleotides

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2
Q

Is a DNA or a RNA molecule larger, and how many nucleotides might each contain?

A

DNA is larger- several million

RNA is smaller- up to several thousand.

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3
Q

Each NUCLEOTIDE has 3 components- what are they?

A

a base, a 5-carbon sugar, and a phosphate group

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4
Q

The nitrogen-containing BASES in nucleic acids are derivatives of ______ or ______.

A

PYRIMIDINE or PURINE

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5
Q

In DNA, the purine bases with double rings are ________ and ___________.

The pyrimidine bases with single rings are _______ and __________.

RNA contains the same bases, except _______ is replaced by ________.

A

PURINE= adenine (A) and guanine (G)

PYRIMIDINE= cytosine (C) and thymine (T)

RNA- THYMINE (5-methyluracil) is replaced by URACIL (U)

know what they look like on page 602

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6
Q

In RNA, the 5-carbon sugar is ______, which gives the letter _______ in RNA.

In DNA, the 5-carbon sugar is ______, which gives the letter ______ in DNA. How is this similar/different to the sugar in RNA?

A

ribose

deoxyribose- similar to ribose except that there is no hydroxyl group (-OH) on C2’. Deoxy means “without oxygen)

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7
Q

What are NUCLEOSIDES?

How are they produced?

A

a combination of a sugar and a base

produced when the nitrogen atom in a pyrimidine or a purine base forms an N-glycosidic bond to carbon 1 (C1’) of a ribose or deoxyribose sugar.

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8
Q

The atoms in the pentose sugars are numbered with _______ to differentiate them from the atoms in the bases.

A

primes

Ex: 1’, 2’, 3’, 4’, 5’

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9
Q

What are NUCLEOTIDES?

A

they are nucleosides in which a phosphate group bonds to -OH on carbon 5 (C5’) of a ribose or deoxyribose sugar. The product is a phosphate ester.

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10
Q

The name of a NUCLEOSIDE that contains a purine ends with _________

a NUCLEOSIDE that contains a pyrimidine ends with ________.

A

osine

idine

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11
Q

The names of the NUCLEOSIDES of DNA add ________ to the beginning of the names.

A

deoxy

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12
Q

The corresponding NUCLEOTIDES in RNA and DNA are named by adding ________.

A

-5’-monophosphate

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13
Q

DNA contains the bases

RNA contains the bases

A

A G C T

A G C U

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14
Q

What are the NUCLEIC ACIDS?

The phosphate link between the sugars in adjacent nucleotides is referred to as a ________ bond.

As more nucleotides are added, a backbone from that consists of alternating ____ and ____ groups.

The bases, which are attached to each ____, extend out from the backbone.

A

Polymers of many nucleotides in which the 3’ -OH group of the sugar in one nucleotide bonds to the phosphate group on the 5’carbon atom in the sugar of the next nucleotide.

PHOSPHODIESTER BOND

sugar; phosphate.

sugar

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15
Q

What is the PRIMARY STRUCTURE of a nucleic acid? What is its function?

A

Each nucleic acid has its own unique sequence of bases, which is knows as its PRIMARY STRUCTURE. It is this sequence of bases that carries the genetic information from one cell to the next.

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16
Q

In any nucleic acid, the sugar at the one end has an unriddled of free 5’-phosphate terminal end, and the sugar at the other end has a free _________ group

A

3’-hydroxyl group

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17
Q

The bases in DNA from a variety of organisms have a specific relationship:

  • the amount of A was equal to the amount of ____
  • the amount of G was equal to the amount of _____

A is always paired 1:1 with ______
G is always paired 1:1 with ______

A

T
C

T
C

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18
Q

DNA is a _______ helix

A

double

19
Q

What is a COMPLEMENTARY BASE PAIR?

A

The pairs A and T & G and C

20
Q

The function of DNA in cells and bacteria is to _______ _________ _______.

What happens as cells divide?

A

preserve genetic information

Copies of DNA are produced that transfer genetic info to the new cells.

21
Q

What happens in DNA REPLICATION?

What begins this process?

A

The strands in the parent DNA separate which allows the synthesis of complementary DNA strands.

The process begins when an enzyme HELICASE catalyzes the unwinding of a portion of the double helix by breaking the HYDROGEN bonds between the complementary bases.

22
Q

What does DNA POLYMERASE do?

A

As a complementary base pairs form, DNA POLYMERASE catalyzes the formation of phosphodiester bonds between the nucleotides.

23
Q

What are DAUGHTER DNAs?

A

The replication process produces two new DNAs called DAUGHTER DNAs that are identical to each other and exact copies of the original parent DNA.

24
Q

What is the function of RNA?

A

makes up most of the nucleic acid found in the cell. It is involved with transmitting the genetic info needed to operate the cell.

25
Q

How are RNA and DNA similar?

How are they different?

A

Similar: molecules are polymers of nucleotides.

Differs:
* the sugar in RNA is ribose rather than deoxyribose found in DNA

  • the base URACIL (U) replaces THYMINE (T)
  • RNA molecules are SINGLE-STRANDED, not double-stranded
  • RNA molecules are much smaller than DNA molecules.
26
Q

What are the 3 major types of RNA in the cells?

Which is most abundant?

A
  1. messenger RNA
  2. ribosomal RNA- most abundant
  3. transfer RNA
27
Q

Describe RIBOSOMAL RNA (rRNA)

What are RIBOSOMES?

A

it is combined with proteins in the ribosomes

RIBOSOMES are the sites for protein synthesis and consist of two subunits (one large and one small)

28
Q

Describe MESSENGER RNA (mRNA)

A

carries genetic information from the DNA, located in the nucleus of the cell, to the ribosomes located in the cytoplasm. Each gene segment of DNA produces a separate mRNA for a particular protein that is needed in the cell.

29
Q

Describe TRANSFER RNA (tRNA)

A

the smallest of the RNA molecules- interprets the genetic information in mRNA and brings specific amino acids to the ribosome for protein synthesis.

Only tRNA can translate the genetic info into amino acids for proteins. There can be more than one tRNA for each of the 20 amino acids.

Drawn as a cloverleaf to illustrate its features

30
Q

What is the ACCEPTOR STEM?

What is an ANTICODON?

A

Acceptor stem= all tRNA molecules have a 3’end with the nucleotide sequence AC, which is known as the acceptor stem.

Anticodon= Each tRNA contains an anticodon, which is a series of 3 bases that complements 3 bases on mRNA.

31
Q

What is TRANSCRIPTION?

What is TRANSLATION?

A

Transcription= in the nucleus, genetic info for the synthesis of a protein is copied from a gene in DNA to make mRNA.

The mRNA molecules move out of the nucleus into the cytoplasm where they combine with ribosomes.

In a process called TRANSLATION, tRNA molecules convert the info in the mRNA into amino acids, which are placed in the proper sequence to synthesize a protein.

32
Q

TRANSCRIPTION: Synthesis of mRNA

  • describe the steps
A
  1. DNA section unwinds
  2. RNA polymerase enzyme uses one of the strands as a template to synthesize mRNA
  3. C pairs with G, U pairs with A
  4. The RNA polymerase moves along the DNA template strand, forming bonds between the bases.
  5. At the termination site, transcription ends and the new mRNA is released.
33
Q

What is the GENETIC CODE?
What are CODONS?

A total of ____ codons are possible from the triplet combinations of A, G, C and U.

A

consists of a series of 2 nucleotides (triplet) in mRNA called CODONS that specify the amino acids and their sequence in the protein.

CODONS have been determined for all 20 amino acids.

64

34
Q

In the TRANSLATION process, tRNA molecules, amino acids and enzymes concert the codons on ________ into a protein.

A

mRNA

35
Q

What is an ANTICODON?

How is a tRNA activated for protein synthesis?

A

each tRNA molecule contains a loop called an ANTICODON- a triplet of bases that complements a codon in mRNA.

activated by ammoniacal tRNA syntheses, which attaches the correct amino acid to the acceptor stem.

36
Q

When does PROTEIN SYNTHESIS begin?

The first codon in mRNA is a _______ codon (AUG), which forms ________ bonds with methionine-tRNA.

A

when mRNA combines with a ribosome.

start codon; hydrogen

37
Q

Describe the process of CHAIN ELONGATION in protein synthesis

A

See Initiation and Chain Elongation paragraph on page 616

38
Q

Describe how CHAIN TERMINATION happens

A

See Chain Termination on page 618

39
Q

What is a MUTATION?

A

a change in the nucleotide sequence of DNA. Such a change may alter the sequence of amino acids, affecting the structure and function of a protein in a cell.

40
Q

What are the 3 types of mutations? Describe each one:

  • SUBSTITUTION (point) mutation
  • FRAMESHIFT mutation
A
  • SUBSTITUTION: the replacement of one base in the template strand of DNA with another- the most common

(NOTE: a silent mutation- if a substitution gives a codon for the same amino acid- no effect)

*FRAMESHIFT- a base in inserted into or deleted from the normal order of bases in the template strand of DNA.

41
Q

EFFECT OF MUTATIONS:

The structure of the resulting protein can be severely altered and it may lose _____ ____.

What is a GENETIC DISEASE?

A

biological activity

When a protein deficiency is hereditary- genetic disease. It is the result of a defective ENZYME in its genetic code.

42
Q

What are VIRUSES?

A

small particles of 3-200 genes that cannot replicate without a host cell. DNA or RNA, but not both.

The only way a virus can replicate is to invade a host cell and take over the materials necessary for protein synthesis and growth.

43
Q

How does a VIRAL INFECTION begin?

A

when an enzyme in the protein coat makes a hole in the host cell, allowing the viral nucleic acids to enter and mix with the materials in the host cell.

44
Q

What is RETROVIRUS?

What is REVERSE TRANSCRIPTION?

A RETROVIRUS contains a polymerase enzyme called _____ ________ that uses the viral RNA template to synthesize complementary strands of DNA.

A

A virus that contains RNA as its genetic material is a RETROVIRUS.

Once inside the host cell, it must first make viral DNA using a process known as REVERSE TRANSCRIPTION.

reverse transcriptase

CHEMISTRY 60 (18 decks)

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