1. Genetics Big Picture Review
Framework 3

2. DNA Double helix – Shape of DNA; two strands of nucleotides
DEOXYRIBONUCLEIC ACID
A type of NUCLEIC ACID
One of the four classes of biological molecules
Function:
Contains GENES- all the codes for our traits
Double helix – Shape of DNA; two strands of nucleotides
Like a ladder that
is twisted

3. Building Blocks of DNA - NUCLEOTIDES
Nucleotide is made of three parts: sugar, nitrogen base and phosphate groups.
Backbone (alternating on the sides of the DNA ladder)
Sugar (deoxyribose)
Phosphate

4. Base Pairing Rules Bases pair with each other like a puzzle
Adenine (A) --- Thymine (T)
Guanine (G) --- Cytosine (C)
Held together by HYDROGEN BONDS
The order of the sequence determines the trait. Ex: ACCTTGGTC - blue eyes ACCTGGGTC – brown eyes

5. Replication Transcription Translation
The central dogma describes how information is sent through a cell to make proteins.
Replication
Transcription
Translation
replication
transcription
translation
RNA is a link between DNA and proteins.

6. DNA Replication –copying of DNA during S-phase of cell cycle
In order to make new cells (cell division) our DNA needs to make copies of itself!

7. Structure of RNA How is that different from DNA??
Single strand of nucleotides
Sugar is called ribose
Ribonucleic Acid
4 Nitrogen Bases
Adenine
Guanine
Cytosine
Uracil ******
How is that different from DNA??

8. TWO types of RNA
Messenger RNA (mRNA) – created during transcription. Carries message from nucleus to ribosome.
Transfer RNA (tRNA) - transfers a specific active amino acid to a growing protein chain on a ribosome during protein synthesis.

9. DNA to RNA - Transcription
DNA cannot leave the nucleus, so it must copy it’s message to messenger RNA (mRNA). THIS IS CALLED TRANSCRIPTION
mRNA then goes from nucleus to the ribosomes in cytoplasm.
mRNA nucleotide triplicates are known as codons
Only 3 nucleotide “letters” long
Ex: AUG, CCG, UAC
Remember RNA has uracil (U) instead of thymine (T)!

10. Protein Synthesis (Translation)
mRNA on ribosome is “translated” into protein.
Process uses tRNA and genetic code to create proteins.
Each codon (3 nitrogen bases) codes for one amino acid
Ex – AUGCCGACUCCUGAA
CCG: proline
ACU: threonine

11. Bio Molecule: Proteins
Function – Structure, support, speed up chemical reactions.

12. Genetic Code 20 amino acids 64 triplet (codon) combinations
*** When AUG is at the beginning of a protein it is a START codon

13. Let’s Translate Protein: Start – Pro – Ser – Gln – Leu – Arg - Stop
mRNA: AUG/CCA/UCG/CAG/UUG/CGG/UGA
Protein: Start – Pro – Ser – Gln – Leu – Arg - Stop
DNA: TACCGGATATCCGCTCTACCGTCGATT
mRNA: AUG/GCC/UAU/AGG/CGA/GAU/GGC/AGC/UAA
Protein: Start – Ala – Tyr – Arg – Arg –Asp – Gly – Ser - Stop

14. Mendel noticed that genes have “FORMS”
He named them: ALLELES
Example of alleles:
Gene for hair color
Blonde allele
Brown allele
Gene for eye color
Blue allele
Brown Allele
Variations of Genes

15. Dominant and Recessive Alleles
Some alleles are expressed over other alleles.
These alleles are known as DOMINANT alleles
DOMINANT alleles are marked by using a capital letter (ex: A C T F)
DOMINANT alleles are NOT always the most popular!!
Polydactyl is a dominant trait!!

16. Recessive Alleles
RECESSIVE alleles are not expressed if there is a dominant allele present!
We use lower case letters for recessive traits (ex: a b d f t)
Examples of recessive alleles:
Blonde hair
Normal vision
Colorblindness
Attached earlobes

17. What color hair do you have??
Inheritance
Because you receive ONE set of chromosomes from your mother and ONE set from your father….
YOU MUST HAVE 2 ALLELES FOR EVERY GENE!
1 from mom and 1 from dad!
Example: Mom gives you an allele for brown hair (B) and Dad gives you an allele for blonde hair (b) your genes for hair color….. Bb
What color hair do you have??

18. GENETIC POSSIBILITIES
Keeping in mind that you have 2 alleles for every gene, the following combinations can result:
HOMOZYGOUS DOMINANT
Both copies are dominant (DD)
Also known as a “purebred” dominant
HOMOZYGOUS RECESSIVE
Both copies are recessive (dd)
ONLY time you will actually SEE a recessive trait!
HETEROZYGOUS
Having one copy that is dominant and one that is recessive (Dd)
Appears as a DOMINANT trait!

19. Describing Genetic Inheritance
There are two different ways of describing someone’s genetics!
GENOTYPE
What the two alleles, or GENES, are that control a specific characteristic
Ex: Aa, bb, CC, Ff, tt
PHENOTYPE
What the organism physically looks like
Ex: Tall, blue, red, freckles, blonde

20. Mendel noticed that genes have “VERSIONS”
He named them: ALLELES
Example of alleles:
Gene for hair color
Blonde allele
Brown allele
Gene for eye color
Blue allele
Brown Allele
Variations of Genes

21. Dominant and Recessive Alleles
Some alleles are expressed over other alleles.
These alleles are known as DOMINANT alleles
DOMINANT alleles are marked by using a capital letter (ex: A C T F)
DOMINANT alleles are NOT always the most popular!!
Polydactyl is a dominant trait!!

22. Recessive Alleles
RECESSIVE alleles are not expressed if it’s heterozygous
We use lower case letters for recessive traits (ex: a b d f t)
Examples of recessive alleles:
Blonde hair
Normal vision
Colorblindness
Attached earlobes

23. What color hair do you have??
Inheritance
Because you receive ONE set of chromosomes from your mother and ONE set from your father….
YOU MUST HAVE 2 ALLELES FOR EVERY GENE!
1 from mom and 1 from dad!
Example: Mom gives you an allele for brown hair (B) and Dad gives you an allele for blonde hair (b) your genes for hair color….. Bb
What color hair do you have??

24. GENETIC POSSIBILITIES
Keeping in mind that you have 2 alleles for every gene, the following combinations can result:
HOMOZYGOUS
In the genotype, both alleles are the same. (dominant or recessive).
Ex: AA bb CC
HETEROZYGOUS
In the genotype, the two alleles are different. (one dominate & one recessive)
Ex: Aa Bb Cc

25. Describing Genetic Inheritance
There are two different ways of describing someone’s genetics!
GENOTYPE
Describes the actual GENES that are inherited
Ex: Aa, bb, CC, Ff, tt
PHENOTYPE
Describes the PHYSICAL look of the trait
Ex: Tall, blue, red, freckles, blonde

26. Other Types of Inheritance
INCOMPLETE DOMINANCE
The dominant trait is not capable of fully masking the recessive gene
Heterozygous genotypes end up with a “blended” phenotype
Ex: RR – red flowers
rr – white flowers
Rr – pink flowers

27. Codominance/Multiple Alleles
Some genes have more than
two (2) dominant alleles
When BOTH dominant alleles are inherited, both dominant alleles are expressed!
Ex: Roan cows
Red is dominant (R)
White is dominant (W)
RW is a red and white cow (roan)

28. ABO Blood Types- Multiple Allele
Human Blood Types are a classic example of codominance and multiple alleles!!
Human Blood Types
Type A blood (dominant)
Type B blood (dominant)
Type AB blood (CODOMINANT)
Type O blood (recessive)

29. Certain traits are found ONLY on the X chromosome!
Sex – Linked Traits
Certain traits are found ONLY on the X chromosome!
These traits are usually RECESSIVE…so happen more often in MALES
Because males only have ONE X chromosome…if they inherit an “infected” X they will automatically have the disorder
A girl will ONLY get the disorder if she inherits TWO infected X’s

30. Polygenic
Some traits can’t be described as “either/or”! They involve a variety of choices because they involve multiple genes coding for them!

31. Mendel’s Laws
After his work with pea plants, Mendel developed two important genetic laws…..
Law of Independent Assortment
When chromosomes line up in pairs during MEIOSIS they do it RANDOMLY
Causes VARIATION

32. Law of Segregation
When chromosomes split during MEIOSIS II, genes do not “follow” each other
You can be a “mix” of DOMINANT and RECESSIVE traits