1. December 19, 2017
Journal: What is the difference between how nucleotides are added to the leading and lagging strands in DNA replication?

2. Mutations, Chromosomes, and Karyotypes

3. Eukaryotic Chromosomes
Made of DNA and protein
Function is to pass on traits

4. When a cell is not dividing, chromosomes are long, thin strands
Before division, they get short & thick and form chromosomes

5. Each organism has a characteristic # of chromosomes
Ex. Humans have 46 chromosomes
Sexually reproducing organisms have 2 sets with same type of genetic info

6. Arranged in a karyotype that shows all our 46 chromosomes as 23 pairs

7. Genes: Sections of chromosomes
Vocabulary
Genes: Sections of chromosomes
Chromatin: DNA + Proteins that make up chromosomes
Centromere: The middle of the chromosome that holds the two sister chromatids together

8. Genes are Sections of Chromosomes

9. Mutations involve Changes in DNA
May be caused by environmental factors called mutagens

10. Chromosome mutations – affect whole chromosome
Mutations may be
Chromosome mutations – affect whole chromosome
Ex. Trisomy 21 aka Down Syndrome
Gene mutations – affect a single gene

11. Types of gene mutations
Substitution - Substitute 1 nucleotide base for another
Insertion - Add one or more extra nucleotides
Deletion- Remove 1 or more nucleotides

12. Substitutions are known as point mutations
Possibly change 1 amino acid
May be “silent”
May introduce stop codon
Insertion/Deletion result in Frameshift
Can change the whole reading frame of the mRNA

14. Mutations may be Helpful Harmful Neutral
Give organism new trait beneficial to their survival
Harmful
Make them less likely to survive
Neutral
No affect

15. Evolution Link: Mutations are the ultimate source of variation