DNA and Replication

There are several genes on a chromosome. They are known as ---------- units

hereditary

Genes must be able to carry ------------- to the next generation

information

Genes must be able to turn the genes into -------------

visible traits

Genes must be able to ---------------- to create ---------- copies for each cell in the body

replicate, identical

Genes must be able to do - things

3

\------------------- used x-ray techniques to begin visualizing the structure of DNA.

Rosalind Franklin

Rosalind Franklin is often not mentioned when discussing DNA because two men used her work to launch their own ---------------------

model of DNA

How do people believe Franklin died?

Radiation posioning

Each nucleotide is a -------------, DNA is a --------------.

monomer, polymer

Nucleotides stack on top of each other through -------------------- and arrange into two strands.

chemical bonding

A nucleotide has 3 parts, these are…

base, sugar, phosphate

The ----------- and ---------- pieces in each nucleotide make up the “backbone” of DNA. They are like the -------- of the ladder.

sugar, phosphate, sides

The ----------- on each strand connect together through hydrogen bonds. They are like the --------- of the ladder.

bases, rungs

There are - different bases in DNA.

4

What are the 4 bases in DNA called?

Adenine, Thymine, Guanine, Cytosine

Adenine and thymine always bond together through - hydrogen bonds.

2

Guanine and cytosine always bond together through - hydrogen bonds.

3

------------------- work helps support the idea that certain bases always bond together.

Erwin Chargaffs

Erwin Chargaff found that the amount of adenine and thymine was always ---------- as well as the amount of cytosine and guanine was always -------.

equal, equal

These base pairings of A=T and G=C are known as -------- rule.

Chargaff’s

DNA has - strands, RNA has - strand.

2, 1

\------ does not have oxygen on the 2’ carbon.

DNA

\------ does have oxygen on the 2’ carbon.

\

RNA

The ------------------ structure of DNA is used as a basis to make exact copies of the DNA each time a cell divided.

complementary

The process of making a copy of DNA is called….

DNA replication

DNA replication occurs during the ------ phase of the cell cycle, before a cell divides.

S

A section of coded DNA instructions used to make proteins or RNA.

gene

DNA replication occurs in - steps

3

In step 1 of DNA replication, ______________ opens the double helix by breaking the hydrogen bonds that link the complementary nitrogen bases between the two strands. The areas where the double helix separates are called _________________________.

DNA helicase, replication fork

During step 2 of DNA replication, at the replication fork, enzymes known as _____________________ move along each of the DNA strands. DNA polymerases add nucleotides to the exposed nitrogen bases, according to the base-pairing rules. Both strands of DNA serve as a________

DNA polymerase, template

In step 3 of DNA replication, Two DNA molecules form that are ________ to

the original DNA molecule.

identical

DNA replication is -------------

semi-conservative

When one original DNA strand & one brand new strand of DNA are found in the helix it is known as

semi-conservative

In the course of DNA replication, errors sometimes occur and the wrong --------- is added to the new strand.

nucleotide

An important feature of DNA replication is that ____________________ have a “proofreading” role.

DNA polymerases

True or false? Replication does not begin at one end of the DNA molecule and end at the other.

True

True or false? The circular DNA molecules found in prokaryotes usually have 3 replication forks that begin at a single point.

False, they usually have 2 replication forks

The replication forks move ---------- each other until they meet on the opposite side of the DNA circle.

away from

In ------------ cells, each chromosome contains a single, long strand of DNA.

eukaryotic

With multiple __________ working in concert, an entire human chromosome can be replicated in about _______________.

replication forks, 8 hours

Replication forks increase the speed of -----------

replication

DNA is a ----------

double helix

\----------- are joined together to form a strand of DNA

nucleotides

Adenine bonds with……..

Thymine

Guanine bonds with…….

Cytosine

2 strands of DNA are held together by……

Hydrogen bonds

Who is credited with the base-pairing rule

Chargaff

DNA strands run…

Antiparrallel