2 - Nucleic Acids

What is the function of nucleic acids?

primary information-carrying molecules

What are the types of nucleic acids?

1. deoxyribonucleic acid

2. ribonucleic acid

Where in the cell is DNA primarily present?

nucleus

Where in the cell is RNA synthesized?

nucleus, then translocated in the cytoplasm

What is the basic structure of nucleic acids?

long chainlike molecules composed of nucleotides

What are the components of each nucleotide?

1. nitrogenous base

2. pentose sugar

3. phosphate group

What is a nucleotide without the phosphate?

nucleoside

What is the difference in the pentose sugars of DNA vs. RNA?

• DNA → deoxyribose sugar, lacks on oxygen atom on the 2 position

• RNA → ribose sugar, OH group on 2 position

What is the result of the difference in pentose sugars of RNA vs. DNA?

RNA is inherently less stable than DNA

Which nitrogenous bases are purines?

adenien & guanine

Which nitrogenous bases are pyrimidines?

cytosine, uracil, & thymine

What replaces the thymine in DNA?

uracil in RNA

Where do nitrogenous bases attach to the sugar molecule?

in the place of the OH group on the 1’ carbon atom

How do bases attach to the pentose sugar?

glycosidic bond

What makes the nucleic acids negatively charged and what is the result?

phosphate group contains one or two negatively charged oxygen atom

• helps in binding of proteins to DNA

• allows DNA to remain straight when denatured

What structures form the backbone of nucleic acids?

composed of alternating sugar and phosphate

Where do phosphate groups link to pentose sugars and what is the result?

• link 3’ carbon of first sugar to 5’ carbon of the next sugar

• phosphodiester bond (2 ester bonds)

What are the two ends of nucleic acids and what is attached at each end?

• 5’ end → free phosphate

• 3’ end → free OH

How are the sugar phosphate backbone strands oriented in DNA?

run in opposite directions, allowing base pairs to compliment one another

What connects the two strands of DNA?

hydrogen bonds between pairs of nucleotides

How many hydrogen bonds are between G & C?

3

How many hydrogen bonds are between A & T?

2

Which bonds are weakest and are between nitrogenous bases?

hydrogen bonds

Which bonds are between the sugar and base?

glycosidic bonds

Which bonds are between the sugars and phosphate?

phosphodiesters

What are the 3 types of RNA?

1. mRNA

2. rRNA

3. tRNA

How is mRNA synthesized?

from a DNA template by transcription

What is the role of mRNA?

• intermediary between DNA & protein

• codes for proteins

What component is added during mRNA synthesis?

7-methylguanosine cap to the 5’ end

What component is added after mRNA synthesis?

poly(A) tail to the 3’ end

What is the function of rRNA?

ensures proper alignment of mRNA, tRNA, and ribosome during protein synthesis

What is the function of tRNA?

contains an amino acid binding site and an mRNA binding site

• carries the correct amino acid to the site of protein synthesis in the ribosome

Define replication

making of DNA from DNA, precedes cell division

What does it mean that DNA is semiconservative?

the two new DNA molecules each contain one parental strand and one new strand

What is transcription?

DNA makes mRNA in the nucleus

What is the translation?

mRNA makes proteins in the cytoplasm

What is the basic flow of genetic information?

DNA → RNA → protein

What is a gene?

a segment of DNA sequence which has a defined product, regulating a character in our body

Define genomics

addresses all genes and their inter-relationships in order to identify their combined influence on the character

Define genetics

the study of heredity, describes how a gene transfers genetic information from parent to offspring

What percent of the human genome can produce protein?

2%