DNA

honors biology

chromosomes

tightly coiled strands of DNA found in the nucleus in eukaryotic cells

telomeres

particular repeated DNA sequences and associated protein molecules found at the end of eukaryotic chromosomes

they shorten instead of important genes

importance of telomeres

U

in RNA, A pairs with

nucleus

where DNA is found in eukaryotic cells

nucleic region

where DNA is found in prokaryotic cells

chromosomes

different organisms have different numbers of _______:

23

pairs of chromosomes in humans

genes

a piece of DNA located in a specific place on a specific chromosome that has instructions to code for one proteins

nucleic acids

DNA and RNA are:

nucleotide monomers

nucleic acids are macromolecules made of:

DNA

deoxyribonucleic acid

RNA

ribonucleic acid

phosphate group, pentose sugar, nitrogenous base

Nucleotides are made of:

double helix

like a twisted ladder

sugar and phosphate

form the backbone

nitrogen bases

bond in the middle with weak hydrogen bonds

covalent bonds

all other bonds besides bases in DNA are held together by:

complementary base pair

nitrogen baes bond only to their:

A

T

C

G

purines

big base (2 carbon rings)

adenine, guanine

types of purines

pyrimidines

small base (1 carbon ring)

cytosine, thymine

types of pyrimidines

weak hydrogen bonds

holds the pairs together

double bond

A is bonded to T via a:

triple bond

C is bonded to G via a:

antiparallel

the strands run in opposite or antiparallel directions

phosphate

____ end is always the 5’ end:

deoxyribose sugar

____ is always the 3” end

5’ to 3’

1 strand runs:

3’ to 5’

2nd strand runs:

DNA

when a cell is ready to divide, it must first copy its:

DNA replication

making an identical copy of DNA

DNA replication

parent DNA makes 2 exact copies of DNA

DNA replication

occurs in nucleus

Cell Cycle

DNA replication occurs in ______ before mitosis so each new cell can have its own FULL copy of DNA:

S phase

DNA replication occurs during the ______ of the Cell Cycle:

same DNA

DNA replication ensures that each new cell will have _____ as the original cell

Helicase

unzips the DNA into two strands

origins of replication

openings in DNA replication are called:

several places

_______ along the DNA will be unzipped at once:

primase

required for DNA synthesis

primase

like a “key” for a car ignition

primase

makes short RNA primers

RNA primers

short pieces of RNA to help get the DNA polymerase started

polymerase

after all nucleotides are added to complement strand RNA primer is removed and replaced with DNA by

ligase

“seals” the gaps in DNA

same time

2 new strands are being created at the ________:

leading strand

new strand made toward the replication fork (only in 5’ to 3’ direction from the 3’ to 5’ template strand)

leading strand

needs one RNA primer made by Primase

leading strand

can be made continuously

lagging strand

new strand synthesis away from replication fork

lagging strand

replicates discontinuously

Okazaki fragments

short pieces of DNA

Okazaki fragments

discontinuous replication creates:

ligase

Okazaki fragments are joined together by:

lagging strand

needs many RNA primers made by Primase

semi conservative replication

two identical DNA molecule are formed, each with an old strand and a new strand

semi conservative replication

each parent strand is now a template (pattern) that determines the order of the new bases

semi conservative replication

forms a “complementary” strand to original strand

semi conservative replication

the newly synthesized double helix is a combination of one old and one new DNA strand

helicase

An enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands.

Polymerase I

“Edit” mistakes of the replicated strand and remove the RNA primers

polymerase III

Add nucleotides in the 5’ to 3’ direction on the leading DNA strand

Ligase

An enzyme that facilitates the joining of DNA fragments

primase

Attaches itself to the 3’ end of the exposed strand, helps attach the RNA primer to the DNA strand

RNA primer

a segment of RNA that is complementary to a given DNA sequence and that is needed to initiate replication by DNA polymerase

Okazaki fragments

Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.

leading strand

The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.

lagging strand

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.

replication fork

a Y-shaped point that results when the two strands of a DNA double helix separate so that the DNA molecule can be replicated

Frederick Griffith

coined the term “transforming factor” as a way to explain that the genetic material of one bacteria can be transferred to another

Hershey and Chase

determined that DNA is the carrier of genetic information – NOT protein --- by using radioactive sulfur and radioactive phosphorus in an experiment with bacteriophages and bacteria

Erwin Chargaff

determined that adenine and thymine occur in roughly the same amounts in DNA, as do cytosine and guanine

Rosalind Franklin

famous for the x-ray diffraction photo B51 that turned out to be the last piece of the puzzle in Watson and Crick’s understanding of the structure of DNA

Avery, McCarty, MacLeod

Through a series of controlled experiments involving enzymes that destroyed various macromolecules, these scientists discovered that DNA was the "transforming factor”

Watson and Crick

Proposed that the exact 3D structure of DNA was two intertwined strands of nucleic acids with the bases pointing inwards towards one another and the sugar-phosphate backbones facing the outside.