bio 1511 - 7.1 DNA Is a Double Helix

DNA

genetic material consisting of a double helix of nucleotides, each containing the sugar deoxyribose

What are 4 types of bases that are included in nucleotide?

Adenine, cytosine, guanine, or thymine

Who were the first people who used two lines of evidence to deduce DNA’s structure?

James Eatons and Francis Crick

Who showed that the amount of guanine in a DNA molecule always equals the amount of cytosine, and the amount to adenine always equals the amount of thymine?

Erwin Chargaff

English physicist Maurice Wilkins and chamist Rosalie Franklin used a technique called _________ to reveal a regularly repeating structure of building blocks, consistent with a helix.

X-ray diffraction

What does the double helix of DNA resemble?

twisted ladder

What are the twin rails of the DNA ladder also known as?

sugar phosphate backbones

The sugar phosphate “backbones” are alternating units of _____ and ____ joined with covalent bonds.

deoxyribose, phosphate

The DNA A-T and G-C base pairs are joined by what kind of bonds?

hydrogen

Adenine and guanine bases have what kind of structure?

double ring

Cytosine and thymine ring structure?

single

Each A-T pair is the same width as a G-C pair because each includes a ____and a _____ base.

double and single-ringed

complementary

the sequent of each strand determines the sequence of the other

genome

all of the genetic material in a cell

gene

a sequence of DNA nucleotides that encodes a specific protein or RNA molecule

chromosome

a DNA molecule wrapped around proteins

nucleotide

building block of nucleic acids

Where is the majority of the genome divided among?

multiple linear chromosomes housed inside of the cell’s nucleus

Genome of bacterial cell typically consists of one circular ______

chromosome

What must the cell do to the chromosome at the bottom of the DNA that is tightly coiled?

unpack chromosome and expose double helix

What is the status of much of the unpacked DNA in terms of its function?

Most DNA has no known function but some encodes RNA and proteins

How many genes are present in the human genome and how are they distributed in the chromosomes?

Human genome comprises 20,000 to 25,000 genes dispersed across its 23 pairs of chromosomes

Label parts of a nucleotide

1)Phosphate group, 2)Deoxyribose, 3)Nitrogenous base

What part of the DNA is shown?

Hydrogen bond

Label the parts

1)Chromosome, 2)Nucleus, 3)Cell, 4)DNA wrapped around protein, 5)Gene