molecular genetics

What is the structure of DNA?

Double helix made of nucleotides (sugar-phosphate backbone + nitrogenous bases: A, T, C, G)

What are the components of a DNA nucleotide?

Deoxyribose sugar, phosphate group, nitrogenous base (A, T, C, G)

Which bases pair together in DNA?

Adenine–Thymine, Cytosine–Guanine

Where is DNA found in eukaryotic cells?

In the nucleus

What is the function of DNA?

Stores genetic instructions for making proteins

What does "antiparallel" mean in DNA?

DNA strands run in opposite directions (5’ to 3’ and 3’ to 5’)

When does DNA replication occur?

During S phase of interphase, before cell division

What is the purpose of DNA replication?

To create an identical copy of DNA

What enzyme unzips DNA during replication?

Helicase

What enzyme adds new nucleotides during replication?

DNA Polymerase

What enzyme connects Okazaki fragments?

Ligase

What is the result of DNA replication?

Two identical double-stranded DNA molecules

What does "semi-conservative" mean in DNA replication?

Each new DNA molecule contains one old strand and one new strand

What is a mutation?

A change in the DNA sequence

What are the main causes of mutations?

Errors in replication, radiation, chemicals

What are the types of mutations?

Substitution, Insertion, Deletion (frameshift)

What is a silent mutation?

A change that does not affect the amino acid

What is a missense mutation?

A change that results in a different amino acid

What is a nonsense mutation?

A change that creates a premature stop codon

What does RNA stand for?

Ribonucleic Acid

How does RNA differ from DNA?

Single-stranded, contains ribose, uses uracil (U instead of T)

What are the nitrogenous bases in RNA?

Adenine, Uracil, Cytosine, Guanine

What are the three types of RNA?

mRNA (messenger), tRNA (transfer), rRNA (ribosomal)

Where is RNA made?

In the nucleus (during transcription)

Where does RNA function?

In the cytoplasm/ribosome

What is transcription?

Process of making mRNA from DNA

Where does transcription occur?

In the nucleus

Which enzyme is used in transcription?

RNA Polymerase

What is the base pairing rule in transcription?

A → U, T → A, C → G, G → C

What is the product of transcription?

mRNA strand that carries the code to ribosome

What is translation?

The process of building a protein from mRNA

Where does translation occur?

At the ribosome (in the cytoplasm)

What does mRNA do?

Carries the genetic code from DNA to the ribosome

What does tRNA do?

Brings amino acids and matches them to codons using anticodons

What does rRNA do?

Helps form ribosomes and catalyze protein synthesis

What is a codon?

Three mRNA bases that code for an amino acid

What is the start codon?

AUG (codes for Methionine)

What are the stop codons?

UAA, UAG, UGA

What is a polypeptide?

A chain of amino acids that folds into a protein

What is the function of proteins in cells?

Structure, enzymes, signaling, regulation

How do you use a codon chart?

Use mRNA codons to find corresponding amino acid

What is a gene?

A sequence of DNA that codes for a specific protein

What is a genome?

The complete set of an organism’s DNA

What is an anticodon?

A 3-base sequence on tRNA that pairs with mRNA codons

What is a frameshift mutation?

Insertion or deletion that shifts the reading frame

How are proteins related to traits?

Proteins determine structure and function, affecting traits

What is the central dogma of biology?

DNA → RNA → Protein

What organelle builds proteins?

Ribosome

What molecule carries genetic instructions?

DNA

What molecule carries amino acids?

tRNA

Which RNA is translated into protein?

mRNA