GUIDED READING: CHAPTER 6.1
WHAT DO GENES LOOK LIKE
Directions: Read pages 128 - 135 and complete the following reading notes. Draw pictures to help you
remember each vocabulary word. (YOU WILL LOSE POINTS IF YOU DO NOT DRAW PICTURES!)
Genes are located on:
chromosomes
Chromosomes are made of:
protein and DNA
DNA is:
deoxyribonucleic acid: hereditary material that
controls all of the activities of the cell,
contains the information to make new cells,
and provides information for making proteins
(define using glossary & draw)
Two things gene material must
able to do:
1. supply instructions for cell processes & for building
cell structures
2. must be able to be copied each time a cell divides so
each cell contains an identical set of genes
A nucleotide is:
a subunit of DNA consisting of a sugar, a phosphate, &
one of four nitrogenous bases
(define using glossary)
The four nucleotide bases are:
(name & draw – see figure 1)
Chargaff’s Rule states:
the amount of adenine in DNA always equals the amount of
thymine, and the amount of guanine always equals the
amount cytosine (A-T, G-C)
Rosalind Franklin used X-ray
Diffraction to:
create images of DNA molecules
Franklin’s images suggested:
DNA has a spiral (helical) shape
Based on the work of others,
Watson & Crick built:
Watson & Crick (using Franklin’s
images) concluded:
models of the DNA molecule
DNA resembles a twisted ‘ladder’ shape (double helix)
with the base-pairs on the inside of the ladder, making up
the ‘rungs’
Based on the model, Watson &
Crick predicted:
how DNA is copied
The sides of the ‘ladder’ are
made of:
alternating sugar and phosphate molecules
The ‘rungs’ of the ‘ladder’ are
made of:
nucleotide bases; adenine paired with thymine, OR
cytosine paired with guanine (each side of DNA is a
complement to the other)
Draw & label the structure:
of DNA (Fig. 5)
Describe how DNA replicates:
1. DNA splits down the middle where the two bases meet
2. Each half serves as a template for a
complementary strand (side)
Incomplete Dominance is:
One trait is not completely dominant over
another, each allele has its own degree of
influence. Ex: true-breeding red snapdragon
flower crossed with a true-breeding white
snapdragon flower produces pink offspring
(define, draw, & explain)
An example of one gene
controlling many traits is:
in a white tiger, the gene for white fur also controls
its blue eye color
An example of many genes
influencing a single trait is:
color of skin, hair and eyes
Factors in the environment that
influence growth are:
healthy diet, exercise and the influence of
family and friends