1. Section 6-4 “Traits & genes”
Write everything that is BLACK

2. KEY CONCEPT Genes encode proteins that produce a diverse range of traits

3. State Standards
4. Genes are a set of instructions encoded in the DNA sequence of each organism that specify the sequence of amino acids in proteins characteristic of that organism. As a basis for understanding this concept:
D. Students know specialization of cells in multi cellular organisms is usually due to different patterns of gene expression rather than to differences of the genes themselves.

4. The same gene can have many versions
Alleles are made up of genes. A Gene is a piece of DNA that directs a cell
to make a certain protein
Each gene has a locus,
a specific position
on a pair of
homologous chromosomes

5. Again a gene is a piece of DNA that directs a cell to make a certain
protein
DNA Brain POP w/ activity

6. An allele is an alternative form of a gene
Each parent donates one allele for every gene
Pea plants have 2 alleles for shape - they receive one from each parent
For shape, there is a wrinkled allele and a round allele

7. What are proteins made of?
Proteins are made up of smaller building blocks called amino acids,
joined together in
chains. There are 20
different amino acids.
Some proteins are just
a few amino acids long,
while others are made
up of several
thousands.

9. Gene Expression: Transcription
The majority of genes are expressed as the proteins they encode. The process occurs in two steps:
Transcription = DNA → RNA
Translation = RNA → protein
Taken together, they make up the "central dogma" of biology:
DNA → RNA → protein.

10. Genes influence the development of traits
All of an organism’s genetic material is called the genome
A genotype refers to the actual genes
A phenotype is the physical expression of a trait

11. Genotype: The gene combination of an organism It consists of 2 alleles
For example:
Pure dominant, 2 dominant genes
Pure recessive, 2 recessive genes
Hybrid, 1 dominant and 1 recessive gene

12. The way an organism looks
Phenotype:
The way an organism looks
No matter what genes are present, phenotype of a tall pea plant is tall and a short pea plant is short

13. Dominant alleles are represented by uppercase letters
A dominant allele is expressed as a phenotype when at least one allele is dominant
A recessive allele is expressed as a phenotype only when two copies are present
Dominant alleles are represented by uppercase letters
Recessive alleles by lowercase letters

14. Mendel’s observed traits
Dominant traits: covers up the other traits
Recessive traits: traits that “disappear”
Rule of Dominance: When a dominant trait is present the recessive trait is hidden

15. R = Red flower r = Purple flower Label the dominant
Step 1:
Label the dominant
and recessive traits
R = Red flower
r = Purple flower

16. Write the genotypes of each
Step 2:
Write the genotypes of each
parent to be crossed
Purple
(since it is recessive it has to be homozygous)
Hybrid Red
(means heterozygous) Rr rr
Rr x rr

17. Set up the punnett square.
Step 3:
Set up the punnett square.
Each parent will give up one gene or the other so there will be one gene per box for each parent
R r r
Rr rr

18. Step 4: Analyze the genotypes
Rr rr
R r r
2 of the 4 (50%) offspring will be pure recessive
2 of the 4 (50%) will be hybrids

19. Step 5: Analyze the phenotypes
Punnett Square Handout
Rr rr
R r r
50% of the offspring
will be red
50% of the offspring
will be purple

20. DNA Structure and Function
DNA Model Lab
DNA contains the genetic information that codes for the RNA and proteins necessary for cell function.
All DNA in the chromosomes has to be copied (replicated) and transmitted to daughter cells via mitosis.
Non-faithful replication or inability to correct errors and damage to DNA results in mutations.
Structure of DNA
A= Adenine
T= Thymine
C= Cytosine
G= Guanine
RNA ONLY
U= Uracil
Four nucleotides (A,T,C,G) are chemically joined through sugar
and phosphate molecules in the backbone.
During synthesis of mRNA (where U is used instead of T)

22. RNA carries DNA’s instructions
The central dogma is the basic concept proposed by Crick (one of the scientists that discovered DNA)
It states that: information flows in one direction from DNA to RNA to proteins

23. Replication Transcription Translation
The central dogma includes three processes:
Brain POP- Mutation
Replication
Transcription
Translation
replication
transcription
translation
Transcription = DNA → RNA
Translation = RNA → protein
RNA is a link between DNA and proteins
Mistake in Replication = Mutation

24. RNA differs from DNA in 4 ways:
RNA has a ribose sugar
RNA has uracil instead of thymine
RNA is a single-stranded structure
RNA can leave the nucleus and go into the cytoplasm DNA can’t

25. Transcription makes three types of RNA
Transcription copies DNA to make a strand of RNA

26. The RNA strand detaches from the DNA once the gene is transcribed

27. Amino acids are coded by mRNA base sequences
Translation converts mRNA messages into polypeptides (protein)
A codon is a sequence of three nucleotides that codes for an amino acid
codon for
Methionine (Met)
Leucine (Leu)

29. A change in the order in which codons are read changes the resulting protein
Regardless of the organism, codons code for the same amino acid

30. Amino acids are linked together by a peptide bond to become a protein
An anticodon is a set of three nucleotides that is complementary (opposite) to an mRNA codon
An anticodon is carried by a tRNA transfer RNA (translation)

31. Transcription vs. Translation Review
Process by which genetic information encoded in DNA is copied onto messenger RNA
Occurs in the nucleus
DNA mRNA (DNA unzipped)
Translation
Process by which information encoded in mRNA is used to assemble a protein at a ribosome
Occurs on a Ribosome
mRNA protein 31

32. Why are proteins important?
Well, for starters, you are made of proteins. 50% of the dry weight of a cell is protein of one form or another. Meanwhile, proteins also do all of the heavy lifting in your body: digestion, circulation, immunity, communication between cells, motion-all are made possible by one or more of the estimated 100,000 different proteins that your body makes.
Here are several examples of how RNA codes for amino acids. These codons are for tryptophan, the amino acid that contributes to the sleepy feeling you may have after eating turkey; phenylalanine, an amino acid used in the aspartame sweetener in diet soda; tyrosine, an important amino acid in intracellular signaling processes; and cystine.

33. Genes control the genetic traits, and genes are DNA, which is organized into chromosomes

34. Codon Bingo Lab
Brain POP’s next slide

35. Brain POP’s
Genetics w/ vocab sheet
Genetic Mutations w/ vocab sheets