1. Central Dogma of Molecular Biology
DNA
Stored information inside nucleus
Copied to make new cells = REPLICATION
RNA
Copied from a piece of DNA (GENE) to make a single protein = TRANSCRIPTION
Moves information from nucleus to cytoplasm
Protein
Information from a single RNA used to make a single protein = TRANSLATION

2. Base Pairing Complementary bases Complementary strands A bonds to T
C bonds to G
Complementary strands
Opposite strands of DNA that can completely base pair to form a double helix

3. DNA Double Helix

4. Chromatin and Chromosomes
DNA associated with proteins
Organizes and packages DNA
Chromosome
Tightly coiled chromatin
Many cells have more than one chromosome
Humans – 46 chromosomes

7. DNA Replication
Each strand of DNA can act as a template for the complementary strand
Enzymes guide replication

8. DNA Replication Enzymes pull apart the DNA strands
Enzymes add complementary nucleotides to each strand

10. Transcription
Part of the DNA molecule is copied to make an RNA molecule

11. The Genetic Code and Genetics
How does DNA encode for protein?
DNA – nucleotide subunits
Nitrogenous bases = information
4 different nitrogenous bases
Protein – amino acid subunits
20 different amino acids

12. How are four nitrogenous bases translated into 20 different amino acids?
Nucleotides form “words” called codons
Each codon codes for a different amino acid
A codon consists of 3 nitrogenous bases
64 different combinations of codons
Only 21 needed (20 amino acids, 1 stop)

13. How is the code read?

14. Transfer RNA’s
“Read” codons
Bring amino acids to the ribosome

22. Mutations
Changes in DNA often but not always cause changes in the protein for which it codes.
Changing a single nucleotide has the potential to dramatically change a protein.

23. Gene

24. Homologous Chromosomes

25. Vocabulary Allele Homozygous Heterozygous Genotype Phenotype
Different versions of a gene
Make different versions of a protein
Homozygous
Same allele on both homologous chromosomes
Heterozygous
Different allele on each homologous chromosome
Often referred to as a hybrid
Genotype
Total set of alleles which can be passed to the next generation
Phenotype
Observable appearance caused by different alleles

26. Naming Genes
All alleles of a gene use the same root letter or word to indicate that it is the same gene
Dominant allele
Phenotype expressed in heterozygous individual
Capitalized letter or word = dominant gene
Recessive allele
Phenotype only expressed in homozygous individual
Lower case letter or word = recessive gene

27. Gregor Mendel’s Law of Segregation
Alleles of a gene segregate from one generation to another
Exact reason not known by Mendel
Today we know assortment occurs during meiosis

28. Garden Pea Self-fertilize Cross-fertilize
Pollen from same flower
Cross-fertilize
Pollen from different flower
To cross is to fertilize (mate)

30. Heterozygous Cross Alleles P p Dominant Phenotype purple Recessive
Phenotype white

31. Genotype Vs. Phenotype Ratio

32. Test Cross
To cross an organism with an unknown genotype with an organism with a known phenotype
PP or Pp X pp
Purple flower could be either PP or Pp
White flower must be pp

33. Multiple Alleles

34. Incomplete Dominance

35. Linked Genes Genes close together on the same chromosome
Sort together during Meiosis
Inherited together

36. Gregor Mendel’s Law of Independent Assortment
Traits are transmitted to offspring independently of one another
Traits that sort independently are on different chromosomes

37. Dihybrid Cross Seed Texture Seed Color R=round r=wrinkled Y=yellow
y=green

38. Sex Chromosomes Humans 46 total chromosomes 23 pairs
22 pairs are called autosomes
common to both males and females
1 pairs are called sex chromosomes
Females
2 X-chromosomes
Males
1 X-chromosome and 1 Y-chromosome

39. Sex Determination
SRY gene present on Y-chromosome triggers male pathway
Female pathway is the default
Hormones determine male and female sex characteristics

40. X-Linked Traits Male inherits only one X-chromosome
From which parent?
Males are Hemizygous for genes on X-chromosome
Female inherits two X-chromosome
One from each parent

41. Queen Victoria Pedigree

42. Dosage Compensation
Both males and females require the same amount of protein coded for in their X-chromosomes
However…
Females 2 X-chromosome
Males 1 X-chromosomes

43. X-inactivation
Female embryos inactivate one X-chromosome at random in each cell when they are days old.
Inactive X-chromosome is called a Barr Body
Females are a mosaic

44. Calico Cats Gene for coat color on X-chromosome
Two alleles Brown and Black

45. Anhydrotic Dysplasia Sweat gland do not develop
Heterozygous females are mosaics