Video: Nucleic Acids and Proteins — Practice Flashcards

Flashcards created from the lecture notes on nucleic acids, DNA/RNA structure, central dogma, and protein biology to aid exam preparation.

What are the two main types of nucleic acids?

DNA and RNA.

In eukaryotic cells, where are DNA and RNA primarily located?

DNA mainly in the nucleus; RNA in the nucleus and cytoplasm; mitochondria and chloroplasts contain DNA and RNA.

Do prokaryotic cells have a nucleus?

No; they lack a nucleus and have DNA and RNA in the cytoplasm.

What are the components of a nucleotide?

A nitrogenous base, a pentose sugar, and a phosphate group.

What is a nucleoside?

A nucleotide without the phosphate group.

What are polynucleotides?

Polymers made up of nucleotides.

How are nucleotides linked in a polynucleotide?

By phosphodiester bonds between the 3' hydroxyl of one nucleotide and the 5' phosphate of the next.

Which ends are 5' and 3' in a polynucleotide?

The 5' end has a phosphate; the 3' end has a hydroxyl group.

What sugar is found in DNA?

Deoxyribose.

Name the DNA bases.

Adenine, Thymine, Cytosine, Guanine.

Name the RNA bases.

Adenine, Cytosine, Guanine, Uracil.

Which bases pair in DNA and how?

A pairs with T; C pairs with G via hydrogen bonds.

What is the overall structure of DNA?

A double helix formed by two antiparallel polynucleotide strands.

What does antiparallel mean in DNA?

The two strands run in opposite 5' to 3' directions.

What type of bonds hold DNA base pairs together?

Hydrogen bonds.

What is the backbone of DNA?

Sugar-phosphate backbone.

If you know the sequence of one DNA strand, can you deduce the other?

Yes, due to complementary base pairing.

What is the Central Dogma of molecular biology?

DNA is transcribed into RNA, which is translated into protein.

Where does transcription occur?

In the nucleus (mRNA synthesis).

What carries genetic information from DNA to the ribosome?

Messenger RNA (mRNA).

How do DNA and RNA differ in structure and sugar?

DNA is usually double-stranded with deoxyribose and thymine; RNA is usually single-stranded with ribose and uracil.

What bases are pyrimidines?

Cytosine and Thymine (Uracil in RNA).

What bases are purines?

Adenine and Guanine.

How many amino acids are used to make proteins?

20.

What are amino acids the monomers of?

Proteins (polypeptides).

What is the general structure of an amino acid?

An α-carbon with an amino group, a carboxyl group, a hydrogen, and an R-group.

What determines the properties of an amino acid?

The R-group.

How are amino acids linked to form polypeptides?

By peptide bonds during dehydration synthesis; the carboxyl group of one amino acid bonds to the amino group of the next.

What are the ends of a polypeptide called?

N-terminus (amino end) and C-terminus (carboxyl end).

How many common amino acids are there?

20.

How are amino acids categorized by their R-group properties?

Nonpolar, Polar, Negatively charged, and Positively charged.

What is a peptide bond also known as?

A C–N (amide) bond linking amino acids.

What determines protein conformation?

The amino acid sequence and the environment (pH, temperature, solvents).

What are the four levels of protein structure?

Primary, Secondary, Tertiary, and Quaternary.

What is the primary structure of a protein?

The unique sequence of amino acids in a polypeptide.

What stabilizes the secondary structure of proteins?

Hydrogen bonds between backbone amide and carbonyl groups forming alpha helices and beta sheets.

What are the two common forms of secondary structure?

Alpha helices and beta pleated sheets.

What is the tertiary structure?

The overall three-dimensional shape of a single polypeptide due to interactions among R-groups.

What is the quaternary structure?

The arrangement of two or more polypeptide subunits into a functional protein.

Sickle-cell disease illustrates a simple change in which level of protein structure?

Primary structure due to a single amino acid substitution in hemoglobin.

Where does the sickle-cell mutation occur?

In the beta chain of hemoglobin.

What determines protein conformation besides sequence?

Environmental factors like pH and temperature.

What is protein denaturation?

Unfolding of a protein with loss of native conformation; may be renatured.

How many calories per gram do fats provide?

Approximately 9 calories per gram.

Calories per gram for proteins and carbohydrates?

Approximately 4 calories per gram.

Are nucleic acids significant energy sources?

No.

Which elements are common in proteins?

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and sometimes Sulfur.

What is the role of enzymes?

Catalysts that speed up biochemical reactions.

What are the main types of enzymes?

Catabolic, Anabolic, and Catalytic.

What energy source has the highest caloric value per gram among fats, proteins, and carbohydrates?

Fats provide about 9 calories per gram.