Which bases pair in DNA?
In the simulation below, build the strand that is complementary to the one shown. In this case, you are not replicating the
... [Show More] strand but completing it.
Thymine
Adenine
Guanine
Cytosine
Cytosine
Thymine
Thymine
Adenine
Guanine
Thymine
To continue, click on the image that you think best represents how DNA normally looks in the cell.
First image
Looking at the images, how many chromosomes are there in a typical human?
46
What do you notice about the chromosomes in both images?
They come in pairs
Why are chromosomes a poor way to think of how DNA is normally stored?
DNA only looks like this during replication
The top image, called a karyogram or karyotype, is from a human female, while the bottom one is from a human male. What major difference do you notice?
The male has a set of mismatched chromosomes
Thinking back to what you learned about genetics, what do the colored bands on the chromosome represent?
Genes
What do the images pointing to each colored band represent?
Phenotypes
From your exploration of DNA structure and biological macromolecules, what do you recall is the function of DNA in the cell?
Information storage
Which of the following characteristics are different between prokaryotic and eukaryotic chromosomes?
Shape
Where is the information stored in DNA?
Base sequence
Looking at the image to the right, what has to be done to chromatin before the information in it can be accessed?
It has to be unwound to uncoiled DNA
From chromatin, two major processes are needed to prepare for DNA replication. Watch the video at right - what processes are needed before new DNA can be made?
DNA has to be uncoiled
Bonds between bases have to be broken
What type of bonds are broken when the strands are split apart?
Hydrogen bonds
It's important to know the base pairing rules for DNA before proceeding. Which of the following are valid pairings for DNA? Select all that apply
A-T
C-G
One last question: How many bases do you think can be added to the new DNA strand each minute by the enzymes in your cells?
2
DNA Race
C with G, G with C, T with A, A with T
What is an isotope?
An atom with a different number of neutrons than normal
What does each model predict for the new DNA molecules? Connect each box on the left to one box on the right. No boxes are connected twice.
Conservative model - One light and one heavy DNA Molecule -Two DNA molecules of different masses between light and heavy
Semi-conservative model - Two DNA molecules halfway between light and heavy
Dispersive Model - Two DNA molecules of different masses between light and heavy
Is the DNA of the first generation grown in the presence of light nitrogen heavier or lighter than the original generation's DNA?
Lighter
What do the results Meselson and Stahl found for the first generation mean?
All DNA used heavy and light nitrogen and has the same mass
What do these results mean for the three proposed models?
The semi-conservative model is supported [Show Less]