DNA Intro

DNA Intro

DNA is an abbreviation for deoxyribonucleic acid. As you may recall, nucleic acids are a type of macromolecule that store information. The deoxyribo part of the name refers to the name of the sugar that is contained in DNA, deoxyribose. DNA may provide the instructions to make up all living things, but it is actually a very simple molecule. DNA is made of a very long chain of nucleotides. In fact, in you, the smallest DNA molecule has well over 20 million nucleotides.

DNA is the material that makes up our chromosomes and stores our genetic information. When you build a house, you need a blueprint, a set of instructions that tells you how to build. The DNA is like the blueprint for living organisms. The genetic information is a set of instructions that tell your cells what to do.

What is dna?

Multiple Choice

What does DNA stand for?

• Deoxyribonucleic Acid

• Ribonucleic Acid

• Deferred Nucleus Antibody

• Double-helix Neutron Acids

Multiple Choice

True or false: DNA contains genes that contain millions of nucleotides.

• True

• False

Nucleotides are composed of three main parts:

a phosphate group.

a 5-carbon sugar (deoxyribose in DNA).

a nitrogen-containing base.

The only difference between each nucleotide is the identity of the base. There are only four possible bases that make up each DNA nucleotide: adenine (A), guanine (G), thymine (T), and cytosine (C).

What is DNA made of?

​nucleotides

​The bases in DNA do not pair randomly. Watson and Crick’s model explained this result by suggesting that A always pairs with T, and G always pairs with C in the DNA helix. Therefore A and T, and G and C, are "complementary bases," or bases that always pair together, known as a base-pair. The base-pairing rules state that A will always bind to T, and G will always bind to C.

Multiple Choice

What are the 4 bases in DNA?

• A, U, G, T

• C, G, T, A

• B, A, C, D

• P, N, A, S

But how do all these pieces fit together? James Watson and Francis Crick won the Nobel Prize in 1962 for piecing together the structure of DNA. Together with the work of Rosalind Franklin and Maurice Wilkins, they determined that DNA is made of two strands of nucleotides formed into a double helix, or a two-stranded spiral, with the sugar and phosphate groups on the outside, and the paired bases connecting the two strands on the inside of the helix

The double helix

Multiple Choice

What is the shape of DNA?

• Single Helix

• Quadruple Helix

• Double Helix

• Triple Helix

The genetic Code

​The various sequences of the four nucleotide bases make up the genetic code of your cells. It may seem strange that there are only four letters in the “alphabet” of DNA. But since your chromosomes contain millions of nucleotides, there are many, many different combinations possible with those four letters. Each person (except identical twins!) has a wholly unique genetic code called a genome. Though these small changes that make us unique are only 0.1% of our entire DNA code.

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​When the genetic code is “read" by cells the sequence of the nucleotide bases tells your cells what color your eyes are, the shape of your ears, and everything else about you!

Multiple Choice

________ contains all the genetic information needed for an organism to grow and survive

• gene

• genome

• proteome

• haplotype

Multiple Choice

The genomes of two unrelated humans are ___% the same.

• 90.0
• 0.1%
• 78%
• 99.9%

Every baby receives a random 50% of their genes from the father and a random 50% from their mother. That means two siblings could get a lot of genes that overlap, or not very many at all!

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The more closely related two individuals are, the more similar their DNA will be. This idea is now used in forensics to make familial DNA matches to suspects. ​

DNA & heredity

Multiple Choice

the passing of genetic traits from parent to offspring.

• heredity
• trait
• gene
• allele

Multiple Choice

A litter of kittens have traits that are similar to both the mother cat and the father cat. Which best explains this situation?

• The kittens are provided the same kind of milk from their mother as they grow.
• The kittens inherit some of their traits from their mother and some from their father.
• The kittens are kept at the same temperatures by their mother when they are first born.
• The kittens are taught by their parents to have similar traits.

Multiple Choice

You are looking at a DNA sample between a cat, dog, and wolf, the dog and cat have 19 differences, the cat and wolf have 24 differences and the dog and wolf have 7 differences. Which are more closely related?

• The cat and dog

• The dog and wolf

• The cat and wolf