DNA Structure and Gene Function

These flashcards cover essential concepts related to the structure of DNA, its role in protein synthesis, and genetic mutation.

What is DNA?

A molecule of nucleic acid made up of many monomer subunits called nucleotides that stores information to produce proteins.

Who conducted an experiment showing DNA can transform bacteria?

Griffith.

What did Hershey and Chase demonstrate?

DNA, not protein, contains genetic information.

What are the components of a nucleotide?

One phosphate group, one molecule of deoxyribose sugar, and one nitrogenous base.

Name the four nitrogenous bases in DNA.

Adenine, Guanine, Cytosine, and Thymine.

What is the DNA structure?

DNA is a double helix comprised of two strands of nucleotides.

How do DNA strands bond?

Hydrogen bonds form between complementary base pairs: Adenine with Thymine and Guanine with Cytosine.

What determines the sequence of one DNA strand?

The nucleotide sequence of the opposite DNA strand.

What is the orientation of DNA strands known as?

Antiparallel.

What is the function of a gene?

To encode a specific protein.

What are the two stages of protein production?

Transcription and Translation.

Where does transcription occur?

In the nucleus.

What does transcription produce?

An RNA copy of a gene using DNA as a template.

What three types of RNA are involved in translation?

Messenger RNA (mRNA), Ribosomal RNA (rRNA), and Transfer RNA (tRNA).

What is a codon?

A three-nucleotide sequence that encodes one amino acid.

Why are ribosomes important?

They facilitate the interaction of mRNA and tRNA to build proteins.

What initiates translation?

Binding of the small ribosomal subunit to mRNA.

What happens during transcription initiation?

RNA polymerase binds to the promoter and unwinds DNA strands.

What are introns?

Sequences in genes that are not used for producing a protein.

What happens to introns during RNA processing?

They are removed from the mRNA.

What is the purpose of the 5' cap and 3' tail on mRNA?

To protect mRNA from degradation.

What is alternative splicing?

A process where different combinations of exons are used to create multiple protein variants from a single mRNA.

How do eukaryotic cells regulate gene expression?

Through multiple levels including transcription factors and RNA processing.

What is a mutation?

A change in a cell's DNA sequence.

What is a point mutation?

A mutation that changes one or a few base pairs in a gene.

What is a frameshift mutation?

A mutation caused by insertion or deletion of nucleotides, altering the reading frame of the gene.

What might be the consequence of a frameshift mutation?

It can cause large changes in protein structure by altering multiple amino acids.

How do eukaryotes differentiate gene regulation from prokaryotes?

Eukaryotes have multiple levels of regulation, typically starting in the nucleus.

What is the role of transcription factors?

They bind to genes and affect RNA polymerase's activity.

What is sickle cell disease caused by?

A single base substitution in a hemoglobin gene.

What can regulatory proteins do in prokaryotes?

They can bind to the operator to either promote or block transcription.

How do lactose and repressor proteins interact in prokaryotes?

Lactose binds to the repressor, changing its shape and releasing it from the operator, allowing transcription.

What happens when a ribosome reaches a stop codon during translation?

A release factor binds to the codon, terminating translation.

What does the large ribosomal subunit do during translation?

It binds to tRNA and helps form peptide bonds between amino acids.

Why are codons important in genetics?

They are the key to translating mRNA into the corresponding amino acid sequence for proteins.