Genetics and Molecular Biology: DNA, RNA, Mutations, and Viruses

What is adenine (A)?

A nitrogenous base found in DNA and RNA, represented by the letter A.

What is AIDS?

Acquired immunodeficiency syndrome, a disease caused by the human immunodeficiency virus (HIV) that weakens the immune system.

What is an anticodon?

A sequence of three nucleotides on a tRNA molecule that is complementary to a specific codon on mRNA.

What is a capsid?

The protein shell that encloses the viral genome.

What is a codon?

A sequence of three nucleotides in mRNA that specifies a particular amino acid.

What is cytosine (C)?

A nitrogenous base found in DNA and RNA, represented by the letter C.

What is DNA ligase?

An enzyme that catalyzes the covalent bonding of adjacent DNA nucleotides.

What is DNA polymerase?

An enzyme that synthesizes new DNA strands by adding nucleotides to a growing chain during DNA replication.

What is an emerging virus?

A newly identified virus that is increasing in incidence or geographic range.

What are exons?

The coding portions of a gene that are expressed in the final mRNA product.

What is a frameshift mutation?

A mutation that shifts the reading frame of the genetic code, often resulting in a completely different translation.

What is the genetic code?

The genetic code is the universal "instruction manual" used by cells to translate the sequence of DNA (or RNA) into proteins. 64 codons map to 20 amino acids

What is guanine (G)?

A nitrogenous base found in DNA and RNA, represented by the letter G.

What is HIV?

Human immunodeficiency virus, the virus that causes AIDS.

What is an intron?

A noncoding, intervening sequence within a eukaryotic gene that is excised from the RNA transcript.

What is messenger RNA (mRNA)?

A type of RNA that carries genetic information from DNA to the ribosome for protein synthesis.

What is a missense mutation?

A mutation that results in a different amino acid being incorporated into a protein.

What is a mutagen?

A physical or chemical agent that causes mutations in DNA.

What is a mutation?

A change in the nucleotide sequence of DNA.

What is a nonsense mutation?

A mutation that introduces a premature stop codon in the protein sequence.

What is a nucleotide?

The basic building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

What is a plasmid?

A small, circular piece of DNA that is separate from chromosomal DNA and can replicate independently.

What is a prion?

An infectious agent composed of protein that can cause neurodegenerative diseases.

What is a promoter?

A DNA sequence that initiates transcription of a particular gene.

What is a retrovirus?

An RNA virus that reproduces by reverse-transcribing its RNA into DNA and inserting it into a host cell's genome.

What is reverse transcriptase?

An enzyme that synthesizes DNA from an RNA template, characteristic of retroviruses.

What is ribosomal RNA (rRNA)?

A type of RNA that, along with proteins, makes up the ribosomes.

What is a ribosome?

A cellular structure that synthesizes proteins by translating mRNA.

What is RNA polymerase?

An enzyme that synthesizes RNA from a DNA template during transcription.

What is RNA splicing?

The process of removing introns and joining exons in a pre-mRNA transcript to produce mature mRNA.

What is the semiconservative model?

A type of DNA replication in which each new DNA molecule consists of one old strand and one newly synthesized strand.

What is a silent mutation?

A mutation that does not change the amino acid sequence of a protein.

What is a start codon?

The codon that signals the start of translation, typically AUG, which codes for methionine.

What is a stop codon?

A codon that signals the termination of translation.

What is a terminator?

A sequence of DNA that signals the end of transcription.

What is thymine (T)?

A nitrogenous base found in DNA, represented by the letter T.

What is transcription?

The process of synthesizing RNA from a DNA template.

What is transfer RNA (tRNA)?

A type of RNA that carries amino acids to the ribosome during protein synthesis.

What is translation?

The process by which the sequence of nucleotides in mRNA is translated into a sequence of amino acids in a protein.

What is a triplet code?

The three-nucleotide sequence in mRNA that corresponds to a specific amino acid.

What is uracil (U)?

A nitrogenous base found in RNA, represented by the letter U.

What is a virus?

An infectious agent that can only replicate inside the living cells of an organism.

anti-

opposite

capsa-

a box

exo-

out, outside, without

-genesis

origin, birth

mutagenesis

the creation of a mutation

intro-

within

liga-

bound or tied

muta-

change

-gen

producing

polynomial

a molecule composed of many nucleotide monomers, covalently bonded together

retro-

backward

semi-

half

trans-

across

-script

write

Compare the structures of DNA and RNA.

DNA is double-stranded and contains deoxyribose sugar, while RNA is single-stranded and contains ribose sugar. DNA uses thymine as a base, whereas RNA uses uracil.

Explain how the structure of DNA facilitates its replication.

The double helix structure of DNA allows it to unwind and separate into two strands, providing templates for the synthesis of new complementary strands during replication.

Describe the process of DNA replication.

DNA replication involves unwinding the double helix, separating the strands, and synthesizing new strands using DNA polymerase, resulting in two identical DNA molecules.

Describe the locations, reactants, and products of transcription and translation.

Transcription occurs in the nucleus, using DNA as a template to produce mRNA. Translation occurs in the cytoplasm, where mRNA is translated into a polypeptide chain using ribosomes, tRNA, and amino acids.

Explain how the "languages" of DNA and RNA are used to produce polypeptides.

DNA's sequence of nucleotides is transcribed into mRNA, which is then translated into a sequence of amino acids, forming a polypeptide chain.

Explain how mRNA is produced using DNA.

mRNA is produced through transcription, where RNA polymerase synthesizes a complementary RNA strand from a DNA template.

Explain how eukaryotic RNA is processed before leaving the nucleus.

Eukaryotic RNA undergoes capping, polyadenylation, and splicing to remove introns and join exons before being transported to the cytoplasm.

Relate the structure of tRNA to its functions in the process of translation.

tRNA has a cloverleaf structure with an anticodon that pairs with mRNA codons and an attached amino acid, facilitating the translation of mRNA into a polypeptide.

Describe the structure and function of ribosomes.

Ribosomes are composed of rRNA and proteins, consisting of a large and a small subunit. They serve as the site of protein synthesis, translating mRNA into polypeptides.

Describe the step-by-step process by which amino acids are added to a growing polypeptide chain.

During translation, the ribosome reads mRNA codons, tRNA brings corresponding amino acids, and peptide bonds form between amino acids, elongating the polypeptide chain.

Diagram the overall process of transcription and translation.

Transcription converts DNA to mRNA in the nucleus, and translation converts mRNA to a polypeptide at the ribosome in the cytoplasm.

Describe the major types of mutations, causes of mutations, and potential consequences.

Major types of mutations include point mutations, insertions, and deletions. Causes can be environmental factors or errors in DNA replication, leading to potential consequences like genetic disorders or cancer.

Compare the structures and reproductive cycles of animal viruses.

Animal viruses can be enveloped or non-enveloped, with either RNA or DNA genomes. Their reproductive cycles involve attachment, entry, replication, assembly, and release from host cells.

Describe three processes that contribute to the emergence of viral disease.

Processes include mutation of viruses, cross-species transmission, and increased human contact with wildlife, leading to new viral strains that can cause disease.

MUTATION, CONTACT BETWEN SPECIES, and SPREAD

Explain how the AIDS virus enters a host cell and reproduces.

The AIDS virus (HIV) binds to CD4 receptors on T cells, enters the cell, integrates its RNA into the host DNA, and uses the host's machinery to replicate and produce new virions.

Describe the structure of prions and explain how they cause disease.

Prions are misfolded proteins that induce abnormal folding of normal proteins in the brain, leading to neurodegenerative diseases.