PBS Review: DNA and Genes

Questions and Answers

DNA is read in segments called _______?

genes

What is a gene?

A particular sequence of nucleotide bases that code for a protein.

What do the sequence of bases determine?

The sequence the amino acids are in which determines the protein.

Describe Step 1 of the production of proteins in a cell.

Transcription: DNA is copied into an mRNA template by RNA polymerase. Signup and view all the answers

Describe Step 2 of the production of proteins in a cell.

Translation: mRNA binds to a ribosome and is read in three bases called codons. Signup and view all the answers

What are codons?

The three mRNA bases that the ribosome reads at a time and this determines the amino acid. Signup and view all the answers

What is the relationship between DNA, codons, mRNA, amino acids, and proteins?

The sequence of DNA determines the codons in mRNA, which determines the sequence of amino acids, which determines the protein being made. Signup and view all the answers

When is tRNA released?

After the amino acid is removed. Signup and view all the answers

How many different amino acids are incorporated in the translation process?

Twenty different amino acids are incorporated in the precise sequence dictated by the three base codons. Signup and view all the answers

What does the process in the ribosome do?

The process in the ribosome builds the polypeptide chains that will become proteins. Signup and view all the answers

What are the possible different properties an amino acid can have?

Positive, negative, or neutral charge. Signup and view all the answers

What is affected by the amino acids present and their order?

The shape of the protein. Signup and view all the answers

What forces affect the shape of the protein?

Van der Waals force, electrostatic charge, S-S, and hydrogen bonds. Signup and view all the answers

What are Van der Waals forces?

Random attractive forces between atoms. Signup and view all the answers

What is electrostatic charge?

Positive amino acids will attract negative amino acids and repel positive amino acids. Signup and view all the answers

What are S-S bonds?

Covalent bonds between amino acids with sulfur, these are stronger forces that hold the protein shape steady. Signup and view all the answers

What are hydrogen bonds?

Bond formed between two molecules that are polar. Signup and view all the answers

Polar amino acids are said to be ________.

hydrophilic Signup and view all the answers

What do hydrophilic amino acids do?

They will attract each other and form hydrogen bonds; they will repel hydrophobic amino acids. Signup and view all the answers

Nonpolar amino acids are said to be _____________.

hydrophobic Signup and view all the answers

Why do fats not mix with water?

Fats are hydrophobic. Signup and view all the answers

What will amino acids do in water?

Hydrophilic amino acids will spread out because they are attracted to water and hydrophobic amino acids will clump because they are repelled by water. Signup and view all the answers

What will amino acids do in oil?

Hydrophilic amino acids will clump because they are repelled by hydrophobic oil and hydrophobic amino acids will spread out. Signup and view all the answers

What is a mutation?

A mutation is a change in one base or bases of DNA. Signup and view all the answers

What is a point mutation?

A change in one base. Signup and view all the answers

What is a frameshift mutation?

An addition or deletion of a base. Signup and view all the answers

What is the effect of a mutation?

The change of a codon which can change the amino acids. Signup and view all the answers

What happens when an amino acid with one property is replaced with an amino acid of another property?

The interactions of the amino acids will change, and the shape of the protein will change. Signup and view all the answers

Can changing just one nucleotide in a gene change the shape of a protein?

True Signup and view all the answers

Study Notes

DNA and Genes

DNA is read in segments called genes.
A gene is a sequence of nucleotide bases coding for a protein.

Amino Acids and Proteins

The sequence of bases in a gene determines the order of amino acids in a protein.
Twenty different amino acids are used in translation, arranged according to codons.

Protein Production Steps

Transcription:
- DNA is transcribed to mRNA by RNA polymerase due to its large size.
- mRNA carries the genetic code from the nucleus to the ribosome.
Translation:
- mRNA binds to a ribosome which reads it in groups of three bases (codons).
- tRNA with matching anticodons brings specific amino acids to the ribosome.
- This process continues until the entire protein is synthesized.

Codons

Codons are the three bases on mRNA that specify which amino acid is added to a growing protein.

Protein Structure Influencing Factors

The shape of a protein is influenced by the properties and order of its amino acids.
Shape is stabilized by several forces:
- Van der Waals forces: Temporary attractions between atoms.
- Electrostatic charge: Attraction between positive and negative amino acids.
- S-S bonds: Strong covalent bonds formed between sulfur-containing amino acids.
- Hydrogen bonds: Weak bonds formed between polar molecules.

Amino Acid Properties

Hydrophilic (polar): Attract water and each other; repel hydrophobic amino acids.
Hydrophobic (nonpolar): Repel water; attract other hydrophobic amino acids.
Fats don't mix with water due to their hydrophobic nature.

Amino Acid Behavior in Different Environments

In water: Hydrophilic amino acids spread out; hydrophobic amino acids clump together.
In oil: Hydrophilic amino acids clump together; hydrophobic amino acids spread out.

Mutations

A mutation is a change in one or more bases in DNA.
Point mutation: Change in a single base.
Frameshift mutation: Addition or deletion of a base affecting the entire downstream sequence.
Mutations can alter codons and subsequently change the amino acids and protein shape.
Even a single nucleotide change can significantly affect protein shape, as seen in conditions like Tay Sachs and Sickle Cell anemia.

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Test your knowledge on DNA and genes with these flashcards. This quiz covers essential concepts such as the definition of genes, the role of nucleotide bases, and the transcription step in protein production. Perfect for biology students looking to reinforce their understanding.