Lecture 7 - Structure and Function of Nucleic Acids and Intro to DNA Replication

What are the main types of nucleic acids?

dna and rna

What are DNA and RNA involved in?

informational processes in the cell

What does ATP do?

store and transport chemical energy

What is cAMP involved in?

intracellular signalling

What are the three parts of a nucleotide?

phosphate group, pentose sugar, nitrogenous base

What bond joins nucleotides together?

phosphodiester bonds

What do phosphodiester bonds form?

sugar phosphate backbone

Which sugar is found in DNA?

deoxyribose

Which sugar is found in RNA?

ribose

What are the four bases found in DNA?

adenine, thymine, cytosine, guanine

What base replaces thymine in RNA?

uracil

Which bases are purines?

adenine and guanine

Which bases are pyrimidines?

cytosine, uracil, thymine

What can nitrogenous bases form?

hydrogen bonds

What is the main function of DNA?

major hereditary material of the cell

Where is DNA found in prokaryotes?

nucleoid

Where is DNA found in eukaryotes?

nucleus, also mitochondria and chloroplasts

What structure does DNA form?

double helix

How are the two DNA strands arranged?

antiparallel

What does antiparallel mean?

dna strands run in opposite directions

What are the complementary DNA base pairs?

a with t, g with c

In which direction is a DNA strand written/synthesised?

5’ to 3’

Where is a new nucleotide added to a DNA strand?

3’ end

What is a chromosome?

dna packed with proteins

What are histones?

proteins that dna wraps around during packing

What is a nucleosome?

dna wrapped around histone proteins

What is the "beads on a string" structure?

nucleosomes along the dna

What is the packing order from least to most condensed?

2nm, 10nm, 30nm, 300nm, 700nm

How is RNA usually structured?

single polynucleotide strand

How does RNA differ from DNA in its bases?

uses u instead of t

What does U pair with in RNA?

adenine

What are the three main types of RNA?

rrna, mrna, trna

What is the function of rRNA?

forms part of ribosome, involved in protein synthesis

What is the function of mRNA?

carries information from dna to ribosome

What does mRNA specify?

amino acid sequence of a polypeptide

What is the function of tRNA?

translates mrna sequence into amino acids during protein synthesis

What is an anticodon?

sequence on trna, binds to a complementary codon on mrna

What does tRNA have an attachment site for?

amino acid

What is DNA replication?

making new copies of dna

What does semiconservative replication mean?

each daughter dna has one parental strand and one new strand

Is DNA replication enzymatic?

yes

What carries out DNA replication?

multi enzyme complex

What are the two important requirements of DNA replication?

must be accurate and fast

What is special about an origin of replication?

contains specific nucleotide sequence

How many origins of replication do prokaryotes have?

one

How many origins do eukaryotes have?

many

What does helicase do?

breaks hydrogen bonds and unwinds dna double helix

What do single-strand binding proteins do?

prevent separated dna strands from re pairing

What does topoisomerase do?

relieves strain caused by dna unwinding

What does primase do?

makes a short rna primer using parental dna as template