Biology Chapter 9 - DNA

A gene is?

a segment of DNA that codes for a protein

Down's Syndrome occurs when an individual has?

an extra chromosome 21

What is the long name for DNA?

deoxyribonucleic acid

The sugar found in DNA is called?

deoxyribose

The twisted ladder shape of DNA is called a?

double helix

The enzymes that break hydrogen bonds and unwind DNA are?

helicase

The DNA molecule is held together by what?

hydrogen bonds

DNA is called the "blueprint of life" because?

it contains the plans for building an organism

RNA differs from DNA in what ways?

it has a different kind of sugar it is single stranded it has uracil

Okazaki fragments form on the:

lagging strand

What is the building block of DNA?

nucleotide

Each strand of DNA is made of linked _____________, which are the subunits that make up DNA

nucleotides

What controls the center of the cell?

nucleus

In the ladder anology of the DNA molecule, the "rungs" of the ladder are?

paired nitrogenous bases

Purine always bonds with what?

pyrimidine

The process by which DNA makes a copy of itself is called?

replication

What is the site of protein synthesis in the cell?

ribosome

The outside of the DNA ladder (the legs) is composed of alternating ___ and phosphates.

sugars

The process by which RNA is made from DNA is called?

transcription

Base pairing is important in DNA replication. Explain how:

(Free) nucleotides bind to exposed strands= A to T and C to G To produce identical copies of DNA

A nucleotide of DNA contains an organic base and two other components. What are the two other components?

(a) Deoxyribose Phosphate group

Pyrimidines have how many rings plus what 2 other things?

1 Nitrogen Ring Tymine Cytosine

In what year did James Watson & Francis Crick discover the structure of DNA?

1953 They also won a Nobel Prize

DNA replication results in?

2 DNA molecules that each contain a strand of the original

Purines have how many rings plus what 2 other things?

2 Nitrogen Rings Adenine Guanine

How many different amino acids are there?

20

Size of the ladder (Backbone) consists of?

5 Carbon Sugars A) Sugar - deoxyribose B) Phosphate Group

How many different codons are possible?

64

The base pair rules states that?

A pairs with T, G pairs with C

Each nucleotide is made of three parts which are?

A phosphate group, a five carbon sugar molecule, and a nitrogen-containing base

Proteins are made in _______ cells?

ALL

What are the four different nitrogen bases in DNA?

Adenine (A) Guanine (G) Thymine (T) Cytosine (C)

Protein is a polymere of?

Amino Acids

Proteins are made up of?

Amino acids (20 total)

The "rungs" of the DNA ladder are made of:

Bases

In 1949, Erwin Chargaff, a biochemist working at Columbia University, in New York City, made an interesting observation about DNA.

Chargaff's data showed that for each organism he studied, the amount of adenine always equaled the amount of thymine (A=T). Likewise, the amount of guanine always equaled the amount of cytosine (G=C).

The element that transformed the bacteria in Griffith's experiments was:

DNA

What did Frederick Griffith's discover?

DNA carried genetic information

Which of the following must happen first in order for DNA replication to occur?

DNA is unwound, by helicase

The process of making a copy of DNA is called?

DNA replication, and it occurs during the synthesis (S) phase of the cell cycle, before a cell divides.

The Hershey-Chase research showed that:

DNA was the molecule of heredity

The five carbon sugars in DNA nucleotides are called?

Deoxyribose, from which DNA gets its full name, deoxyribonucleic acid.

DNA polymerase is involved in DNA replication. Explain how:

Forms new strands of DNA (molecules) By joining together (single) nucleotides bound to existing strands

A stretch of chromosome that codes for a trait can be called a(n)?

Gene

DNA is wrapped tightly around proteins called what?

Histones

Explain how DNA replicates:

Hydrogen bonds broken; DNA helicase; Semi-conservative replication/ both strands used (as templates); Nucleotides line up;Complementary/ specific base pairing/ A and T/ C and G; DNA polymerase;

The Rate of Replication in Eukaryotes

In eukaryotic cells, each chromosome contains a single, long strand of DNA. The length presents a challenge: The replication of a typical human chromosome with one pair of replication forks spreading from a single point, as occurs in prokaryotes, would take 33 days! To understand how eukaryotes meet this challenge, imagine that your class has to carry 25 boxes to another building. Carrying one box over, returning, carrying the second box, and so on, would be very slow. It would be much faster if everyone in the class picked up a box so that all of the boxes could be carried in one trip.

DNA is a polymere of?

Nucleotides

What is an allele?

One form of a gene

A long chain of repeating units is called?

Polymere DNA is polymere of nuclotide Protein is polymere of amino acid

Polypeptide = what?

Protein

Every living cell contains what 4 things?

Proteins Cell Membrane Cell Organelles Enzymes

2 Categories of Nitrogen Bases are?

Purines and Pyrimidines

Okazaki fragments occur during?

Replication

The Rate of Replication in Prokaryotes

Replication does not begin at one end of the DNA molecule and end at the other. The circular DNA molecules found in prokaryotes usually have two replication forks that begin at a single point. The replication forks move away from each other until they meet on the opposite side of the DNA circle.

The sugar in RNA is _____, the sugar in DNA is _______

Ribose (RNA) Deoxyribose (DNA)

Role of Enzymes in DNA Replication Step 1:

Step 1: Before DNA replication can begin, the double helix unwinds. This is accomplished by enzymes called DNA helicases. DNA helicases open the double helix by breaking the hydrogen bonds that link the complementary nitrogen bases between the two strands. Once the two strands are separated, additional proteins attach to each strand, holding them apart and preventing them from assuming their double-helical shape. The areas where the double helix separates are called Replication Forks because of their Y shape.

Role of Enzymes in DNA Replication Step 2:

Step 2: At the replication fork, enzymes known as DNA Polymerase move along each of the DNA strands. DNA polymerases add nucleotides to the exposed nitrogen bases, according to the base-pairing rules. As the DNA polymerases move along, two new double helices are formed.

Role of Enzymes in DNA Replication Step 3:

Step 3: Once DNA polymerases have begun adding nucleotides to a growing double helix, the process continues until all of the DNA has been copied and the polymerases are signaled to detach. This process produces two DNA molecules, each composed of a new and an original strand. The nucleotide sequences in both of these DNA molecules are identical to each other and to the original DNA molecule.

The ladder consists of alternating what?

Sugar and Phosphate Groups

How bases pair one side:

T - A A - T C - G G - C T - A G - C C - G

A DNA strand has the following bases: A A G C C A. What are the bases on its complimentary strand?

T T C G G T

DNA is a ladder

The Ladder of Life The Master Molecule The Blue Print of Life

The organic bases present in DNA allow DNA to store information about the sequence of amino acids in a protein. Explain how?

The sequence of bases determines the sequence of amino acids Three bases code for one amino acid

Adenine always pairs with what?

Thymine (T)

The amount of adenine and thymine and of guanine and cytosine varies between different organisms. True or False?

True

True or False: Proteins are the most common organic compound?

True

True or False: Without protein there is no life?

True

True or False: You only want kidney cells/genes in your kidney?

True

Which of the following is found on RNA but not DNA?

Uracil

The two men who established the structure of DNA were?

Watson and Crick

The Winding Staircase

Watson and Crick determined that a DNA molecule is a double helix—two strands twisted around each other, like a winding staircase.