Transcript DNA codes for PROTEINS

Review
1. Describe how chromosomes and DNA are
related.
2. The DNA molecule is shaped like a twisted
ladder. (a) What are the sides of the ladder
made of? (b) What are the rungs made of? (c)
Name each of the molecules that make up the
rungs.
3. Describe how the DNA molecule replicates.
4. Which base joins with each base listed below?
(a) cytosine (b) thymine (c) adenine (d) guanine
Answers…
1. Chromosomes are made up of DNA.
2. (a) The sides of the “ladder” are made of
phosphate and sugar joined together. (b) The rungs
are made of nitrogenous bases. (c) The nitrogenous
bases are adenine, thymine, cytosine, and guanine.
3. To replicate, a DNA molecule splits and new
bases are added onto each of the open sides to
make two identical DNA molecules.
4. (a) cytosine pairs with guanine (b) thymine pairs
with adenine (c) adenine pairs with thymine (d)
guanine pairs with cytosine
Marks
Science 9 Biology Marks
3 tests
30%
3 major assignments
30%
Daily assessment and quizzes 20%
Notebook
10%
Participation
10%
How genes make proteins
Science 9 Biology lesson #4
What you need to learn
• that members of the same species have the
same number genes but different traits.
• the difference between DNA and RNA
• that amino acids are the building blocks of
proteins
• some common proteins and their functions
• how ribosomes make proteins using RNA and
amino acids
Genes are stored on DNA
• A gene is a short section of DNA that
contains the instructions to make a
specific protein.
The Genome
• All of an organism’s genes (its entire DNA) is
called the genome.
• The human genome = 23 pairs of
chromosomes
• almost every cell in the body has those
chromosomes
Genes to Proteins
(Protein synthesis)
1. A gene segment of DNA separates and an
RNA molecule is constructed from one half of
the DNA. RNA is very similar to DNA except it
has only one strand (DNA is double strand)
2. The RNA strand travels from the nucleus to
the cytoplasm.
3. The ribosome “reads” the instructions on the
RNA and assembles the protein out of amino
acids floating in the cytoplasm.
Traits
• All members of the same species have the
same number and types of genes. They are
responsible for making hair, nails, eyes, and
every other human characteristic.
• Within a species, there are different versions
of the same gene. The different versions
produce slightly different variations, or traits,
for each characteristic.
Review Questions
1. Describe how DNA and genes are related.
2. How is the genetic code transferred from the
nucleus into the cytoplasm?
3. How is RNA different from DNA?
4. Place the following events of protein synthesis in
the correct order. (a) Ribosomes manufacture
protein. (b) RNA is formed from a gene.(c) Part
of a DNA molecule “unzips.” (d) RNA carries the
genetic code into thecytoplasm. (e) Amino acids
attach to ribosomes.
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Answers
1. Describe how DNA and genes are related.
2. How is the genetic code transferred from the
nucleus into the cytoplasm?
3. How is RNA different from DNA?
4. Place the following events of protein synthesis in
the correct order. (a) Ribosomes manufacture
protein. (b) RNA is formed from a gene.(c) Part
of a DNA molecule “unzips.” (d) RNA carries the
genetic code into thecytoplasm. (e) Amino acids
attach to ribosomes.