CH1: Nucleic Acids

Question 1

What are examples of nucleic acids?

Answer 1

DNA and RNA

Question 2

What is the structure of nucleotides

Answer 2

Nitrogenous base, sugar and phosphate group

Question 3

What is the structure of nucleic acids

Answer 3

macromolecules formed from repeating units of nucleotides/bases

Question 4

What are the nitrogenous bases of nucleic acids

Answer 4

Adenine, guanine and cytosine are in both DNA and RNA
Uracil is in RNA
Thymine is in DNA

Question 5

What are the base pairings of nucleic acids

Answer 5

Adenine and Thymine/Uracil
Guanine and Cytosine

Question 6

What base pairing has 2 hydrogen bonds

Answer 6

A-T / A-U
This means it is less stable

Question 7

What base pairing has 3 hydrogen bonds

Answer 7

C-G
This makes it more stable

Question 8

What is the difference between DNA and RNA?

Answer 8

DNA:
- Consists of a nitrogenous base core of either a purine or pyrimidine, a pentose sugar (deoxyribose) and phosphate
- One less oxygen compared to RNA (think “deoxy”)
- More stable
- Double stranded molecule that contains genetic information
RNA:
- Consists of a nitrogenous base core of either a purine or pyrimidine, a pentose sugar (ribose) and phosphate
One more oxygen than DNA
- Less stable
- Single stranded molecule that contains the instructions for DNA to form proteins and carry out cell functions

Question 9

Does DNA or RNA contain AGCT?

Answer 9

DNA

Question 10

Does DNA or RNA contain AGCU?

Answer 10

RNA

Question 11

What are the pyrimidines (1 Ring)?

Answer 11

Cytosine, Thymine and Uracil

Question 12

What are the purines (2 rings)?

Answer 12

Adenine and Guanine

Question 13

What is the first step of protein synthesis?

Answer 13

Cell Signaling
Cell signaling communicates the need to synthesize a protein to the nucleus
This occurs in the cell membrane due to membrane proteins

Question 14

What is step two of protein synthesis?

Answer 14

Transcription
Transcription of a gene in the nucleus results in the synthesis of a strand of mRNA
This occurs in the nucleus

Question 15

What is the third step of protein synthesis?

Answer 15

Translation and Elongation
The mRNA strand leaves the nucleus, binds to ribosomes and directs protein translation with the help of tRNA subunits and their associated amino acids. This elongation process results in the production of a peptide strand
This process occurs in the nucleus, but also leaves the nucleus in this process

Question 16

Photo overview of Protein synthesis

Answer 16

Question 17

How does cell replication occur

Answer 17

DNA unravels and nucleotides are added to each strand to make two sets
During cell division the two unravel, with each forming a template for synthesizing a new strand through complementary base pairing

Question 18

What is transcription

Answer 18

The process by which the genetic information (through the sequence of base pairs) in a single strand of DNA makes a specific sequence of bases in a messenger RNA
A single strand of DNA can make many copies of the corresponding mRNA, which will become multiple templates for the assembly of a specific protein
DNA -> mRNA
Occurs in the nucleus

Question 19

What are introns

Answer 19

Part of transcription
Intervening sequences
Regions that are part of the gene but do not code for a protein product
They have to be removed from the mRNA before it is translated into protein

Question 20

What are exons

Answer 20

Part of transcription
Expressed sequences
The gene segments that get both transcribed and translated into the protein product
No post-translational processing

Question 21

What is translation

Answer 21

The process by which genetic information in an mRNA molecule is turned into the sequence of amino acids in the protein
After the mRNA is synthesized in the nucleus, the mRNA is exported into the cytoplasmic matrix, where it is attached to ribosomal RNA (rRNA) of the ribosomes of the RER or to the free standing ribosomes
mRNA -> Protein
in the cytoplasm

Question 22

What is elongation

Answer 22

Once amino acids are positioned, the peptide bonds are formed between the aligned amino acids in this process
This extends the polypeptide chain of the protein product by translation

Question 23

What are codons?

Answer 23

The genetic code for specifying the amino acid sequence of a protein resides in the mRNA in the form of three-base sequences
Each codon codes for a single amino acid
Although a given amino acid may have several codons (e.g., the codons CUU, CUC, CUA, and CUG all code for the amino acid leucine), codons can code for only one amino acid
Three-base sequence in a DNA or mRNA molecule that specifies the location of a single, particular amino acid in a polypeptide chain

Question 24

What are anticodons?

Answer 24

Three-base sequences of nucleotides within transfer RNA (tRNA) molecules
For example, because codons that code for leucine are sequenced CUU, CUC, CUA, or CUG, the only tRNAs to which an activated leucine can be attached would need to have the anticodon sequence GAA, GAG, GAU, or GAC

Question 25

What signals the end of elongation?

Answer 25

"nonsense" codon that does not code for any amino acid

Question 26

Are all genes expressed in specialized organ cells?

Answer 26

No, only a portion of genes are expressed Regulation of gene expression occurs at three different levels