Name________________________________________
Date: ___________________
DNA, Genes, and Chromosomes
Read and answer the questions. High-lite answers in yellow.
Have you ever wondered why children share some characteristics with their
parents but not others? Do they have the same eye color? Can a particular
disease “run in a family”? What makes humans different from other organisms?
The answer is deoxyribonucleic acid (DNA).
What makes you similar to other humans? _____________________________________
_______________________________________________________________________________
What traits do you see that are similar between members of your family?
_______________________________________________________________________________
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Why do we share more characteristics in common with other humans than we do
with dogs? ____________________________________________________________________
_______________________________________________________________________________
DNA is a large molecule found in the cells of all living things. If a cell has a
nucleus, the DNA is in the nucleus. In cells that do not have a nucleus, the DNA is
in the cytoplasm. This molecule carries the code of life. DNA determines what
traits, or characteristics, are passed down from one generation to the next. The
passing of genes from one generation to the next is called heredity. The study of
how traits are passed from parents to offspring is genetics.
Where in a cell can DNA be found (name two places)? ________________________
_______________________________________________________________________________
What is heredity? ____________________________________________________________
_____________________________________________________________________________
What is the study of how traits are passed on called? _________________________
A molecule of DNA is shaped like a twisted ladder. This shape is called a
double helix. The sides of the ladder are alternating sugars and phosphates. The
rungs of the ladder are made up of
paired compounds called bases.
There are four bases (A,T,C,G), and the
order in which they are attached to
the molecule is what makes up the
code.
What is the shape of a DNA molecule?
____________________________________
What makes up the sides of the
ladder?
______________________________________
What makes up the rungs of the
ladder? ______________________________________
Think about letters of the alphabet. If you rearrange the letters in a word,
you change the meaning. For example, the words diet and tide are made of the
same four letters, but the two words have entirely different meanings. Similarly,
each combination of hundreds of bases in a DNA molecule codes for a different
trait.
What determines the DNA code for traits?
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