AICE Biology Chapter 6

What are the key features of a genetic molecule?

Ability to store information and the ability to copy itself accurately.

What was the belief about genetic material before the 1940s?

Scientists believed proteins were the genetic material.

What evidence emerged in the 1940s to 1950s regarding genetic material?

DNA was proven to be the genetic material.

What does DNA stand for?

Deoxyribonucleic acid.

What does RNA stand for?

Ribonucleic acid.

What are macromolecules known as nucleic acids?

DNA and RNA, found first in the nucleus.

What are the monomers of DNA and RNA?

Nucleotides.

What are the three components of a nucleotide?

Nitrogen-containing base, pentose sugar, and phosphate group.

Name the nitrogenous bases of DNA.

Adenine (A), Guanine (G), Thymine (T), Cytosine (C).

Name the nitrogenous bases of RNA.

Adenine (A), Guanine (G), Uracil (U), Cytosine (C).

What are purines?

Nitrogenous bases with two rings: Adenine (A) and Guanine (G).

What are pyrimidines?

Nitrogenous bases with one ring: Thymine (T), Cytosine (C), Uracil (U).

What sugar does DNA contain?

Deoxyribose.

What sugar does RNA contain?

Ribose.

What is ATP?

Adenosine triphosphate, a nucleotide made of adenine, ribose, and three phosphate groups.

What is a dinucleotide?

Two nucleotides joined by a phosphodiester bond.

Who discovered the structure of DNA?

James Watson and Francis Crick in 1953.

Describe the structure of DNA.

A double helix made of two antiparallel strands.

What bonds hold the two strands of DNA together?

Hydrogen bonds between complementary bases.

What is complementary base pairing in DNA?

A pairs with T (2 hydrogen bonds), G pairs with C (3 hydrogen bonds).

What is the process of DNA replication?

DNA unzips, and each strand serves as a template for a new complementary strand.

Describe the leading strand during DNA replication.

Copied continuously in the same direction as the DNA unwinds.

Describe the lagging strand during DNA replication.

Copied in short fragments called Okazaki fragments in the opposite direction of unwinding.

What enzyme is responsible for joining Okazaki fragments?

DNA ligase.

What is the method of DNA replication called?

Semi-conservative replication.

What is a gene?

A length of DNA that codes for a specific polypeptide or protein.

What is the genetic code?

The sequence of DNA bases that codes for the sequence of amino acids in proteins.

What is the triplet code?

A sequence of three DNA bases (codon) that codes for one amino acid.

Why is the genetic code considered universal?

The same codons code for the same amino acids in all living organisms.

What signals the start and stop of protein synthesis?

Start codons (e.g., TAC) signal the beginning, and stop codons signal the end.

What occurs during transcription?

RNA polymerase copies genetic information from DNA to mRNA.

Where does transcription take place?

In the nucleus.

What is the process of translation?

Conversion of the mRNA sequence into an amino acid chain at the ribosome.

What does tRNA do during translation?

Transfers amino acids to the ribosome.

What are mutations?

Random changes in the genetic material.

What types of mutations exist?

Gene mutations and chromosome mutations.

What causes mutations?

DNA replication errors and mutagens like radiation and carcinogens.

What is a substitution mutation?

When one base is replaced by another in the DNA sequence.

What is a deletion mutation?

When a base is removed from the DNA sequence.

What is an insertion mutation?

When an extra base is added to the DNA sequence.

What is a frame-shift mutation?

A mutation caused by insertion or deletion that shifts the reading frame of codons.

What are the effects of gene mutations on proteins?

They can alter the amino acid sequence, changing the protein's structure and function.

What is semi-conservative replication?

DNA replication where each new molecule has one old strand and one new strand.

What is the role of RNA polymerase in transcription?

RNA polymerase binds to DNA and synthesizes mRNA.

What is an anticodon?

A set of three bases on tRNA that pairs with a codon on mRNA.

What occurs during mRNA processing in eukaryotes?

Introns are removed and exons are joined together.