ch 9 BSC2010

Nucleic acids

Macromolecules made up of nucleotides, essential for genetic information and protein synthesis.

DNA (Deoxyribonucleic acid)

The genetic material that carries the instructions for life, composed of two strands forming a double helix.

RNA (Ribonucleic acid)

Single-stranded nucleic acid involved in protein synthesis, differs from DNA in structure and function.

Nucleotide

The building block of nucleic acids, consisting of a phosphate group, a sugar, and a nitrogenous base.

Adenine (A)

A purine base found in DNA and RNA, pairs with thymine (T) in DNA and uracil (U) in RNA.

Thymine (T)

A pyrimidine base found in DNA, pairs with adenine (A). Not present in RNA.

Cytosine (C)

A pyrimidine base found in both DNA and RNA, pairs with guanine (G).

Guanine (G)

A purine base found in both DNA and RNA, pairs with cytosine (C).

Hydrogen bonds

Weak interactions that hold the two strands of DNA together, specifically between nitrogenous bases.

Complementary base pairing

The principle that dictates adenine pairs with thymine (or uracil in RNA), and cytosine pairs with guanine.

DNA replication

The process by which a DNA molecule makes a copy of itself, involving several key enzymes and steps.

DNA helicase

An enzyme that unwinds and separates the double-stranded DNA during replication.

DNA polymerase

The enzyme that adds nucleotides to a growing DNA strand; requires a primer to initiate synthesis.

Leading strand

The DNA strand that is synthesized continuously in the same direction as the replication fork.

Lagging strand

The DNA strand that is synthesized discontinuously in fragments (Okazaki fragments) opposite to the direction of the replication fork.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during DNA replication.

RNA primer

A short strand of RNA that provides a starting point for DNA synthesis by DNA polymerase.

DNA ligase

An enzyme that joins Okazaki fragments together on the lagging strand by forming covalent bonds.

Genome

The complete set of chromosomes in an organism, containing all the genetic information.

Chromosome

A structure within the cell nucleus that contains DNA and associated proteins, carrying genetic information.

Central dogma of molecular biology

The process by which the information in genes flows into proteins: DNA -> RNA -> Protein.

Gene

A segment of DNA that contains the instructions for making a specific protein or function in the cell.

Histone proteins

Proteins that assist in the packaging of DNA into a compact, organized structure called chromatin.

Telomeres

The protective ends of chromosomes that shorten with each cell division, implicated in aging.

Complementary

Referring to how the bases pair in DNA: adenine with thymine and guanine with cytosine.

Transcription

The process in which a segment of DNA is copied into RNA.

Translation

The process in which messenger RNA (mRNA) is decoded outside the nucleus and synthesizes proteins.

What is DNA?

DNA (Deoxyribonucleic acid) is the hereditary material in humans and almost all other organisms.

What shape does DNA have?

DNA has a double helix structure.

What are the four nitrogenous bases in DNA?

The four nitrogenous bases are adenine (A), thymine (T), cytosine (C), and guanine (G).

What process copies DNA?

DNA replication is the process that copies DNA.

What enzyme unzips the DNA double helix during replication?

DNA helicase is the enzyme that unzips the DNA double helix.

Which base pairs with adenine in DNA?

Thymine pairs with adenine in DNA.

What is a gene?

A gene is a segment of DNA that contains the instructions for making a specific protein.

What is the central dogma of molecular biology?

The central dogma states that genetic information flows from DNA to RNA to protein.

What role does RNA play in protein synthesis?

RNA translates the genetic code from DNA into proteins during the processes of transcription and translation.

What are telomeres?

Telomeres are the protective ends of chromosomes that prevent degradation during cell division.