Joanna Liu Chapter 4: DNA & Gene Expression

What is DNA?

The molecule that carries the genetic instructions

What is DNA made of?

Nucleotides, Phosphate group, deoxyribose sugar

What shape is DNA?

Double helix

What is each nucleotide made of?

5 carbon sugar, a phosphate group, and a nitrogenous base

What is the backbone of DNA?

Phosphate

How are the rings of the ladder connected together?

The hydrogen bonds between base pairs

What are the four nitrogen bases?

Guanine, Adenine, Cytosine, Thymine

How do the nitrogenous bases of DNA pair?

Guanine pairs with Cytosine and Thymine pairs with Adenine

What do the sequence of bases code?

It codes for proteins

How does Biotechnology use DNA’s stability and reproducibility?

PCR, Gene sequencing, Genetic Engineering

What does understanding the structure of DNA allow?

Knowing how DNA’s structure dictates its function is the foundation for modern biotechnology and genetic medicine.

When does DNA replication occur?

During the S phase of the cell cycle

What is semiconservative replication?

Half is the old strand and half is the new strand

How does the DNA double helix unwind?

By using the DNA Polymerase

What is replication fork?

the region where DNA is unraveling/unwinding

What is the leading strand?

The strand building continuously

What is the lagging strand?

The strand building in fragments

What type of DNA does bacteria have?

Circular DNA

What is the DNA polymerase?

A enzyme that separates the DNA strands

What is the Origin Recognition Complex?

It detects and binds to the origin of replication and marks where replication begins

What is Helicase?

unwinds the DNA double helix by breaking hydrogen bonds

What is the purpose of the template DNA?

to serve as a guide to build complementary new strands

What is the Replication bubble?

forms where DNA separated and expands as replication proceeds in both directions

What is the Replication fork?

Y shaped region where DNA is actively unwound and copied

What is topoisomerases?

prevents DNA from unwinding ahead of the fork by making temporary cuts

What are single-strand binding proteins?

binds to unpaired DNA strands to keep them from reattaching

What are RNA primers?

Short RNA sequences synthesized to start DNA synthesis

What is primase?

Enzyme that synthesizes RNA primers on both strands

What are Okazaki fragments?

Short stretches of newly synthesized DNA joined later into a continuous strands

What is DNA ligase?

Enzyme that joins the okazaki fragments

What are histone proteins?

Small, positively charged proteins that bind DNA and allows it to coil tightly

What are histones?

proteins that help organize and pack DNA into chromatins

What are nucleosomes?

Basic unit of chromatin consisting of DNA wrapped around histones

What is chromatin?

The entire DNA-protein complex visible in the nucleus

What are euchromatin?

loosely packed chromatins that are active

What are heterochromatin?

tightly coiled chromatins that are inactive

Who discovered transformation?

Frederick Griffith

When was transformation discovered?

1928

What was the end conclusion of DNA transformation?

Proved that heritable information could be passed between organisms without direct reproduction

What is transcription?

The process of converting the DNA template into RNA form for creating proteins

What is mRNA?

Messenger RNA, single stranded RNA copy of DNA and carries genetic information of ribosomes

What is ribose phosphate backbone?

RNA’s sugar-phosphate backbone made of ribose instead of deoxyribose

What is a codon?

A sequence of 3 RNA bases that code for amino acids

What is a polypeptide?

What is an enzyme?

A natural catalyst formed from polypeptides

What is the central dogma of molecular biology?

DNA —> mRNA —> Protein —> Trait