Chromosomes, Cell Division & DNA
concepts from
Chapters 16 & 17 & 18
Chapter 16 outline*

DNA and the Chromosome
– The building blocks
– Description of a karyotype

Somatic Cells
– Cell cycle
– Mitosis

Reproductive cells
– Meiosis (* this topic can be found in ch. 17)
What is…

DNA

A Chromosome
DNA is composed of millions of nucleotides
THE DNA MOLECULE
Diploid Cell
23 pairs or 46 chromosomes
44 autosomes
2 sex chromosome
How do all of our nonreproductive cells divide & keep
46 chromosomes?
Somatic Cell Division
The cell cycle
Mitosis
prophase
anaphase
metaphase
telophase
Mitosis
animation links
http://highered.mcgraw-hill.com/olc/dl/120073/bio14.swf
Mitosis (includes cell wall)
How many chromosomes do our
reproductive cells have and how do
they divide?
23 chromosomes
&
Meiosis
Animation LINKS
http://highered.mcgraw-hill.com/olc/dl/120074/bio19.swf
Meiosis I and II
http://highered.mcgraw-hill.com/olc/dl/120074/bio17.swf
Mitosis versus meisosis
MEISOSIS and FERTILZATION
23 + 23 =46
23 chromosomes
Ch. 18 concept: How does DNA affect your phenotype?
Central Dogma
DNA
RNA
Protein
The next 6 slides will refer to material found in chapter 18.
DNA
Nucleus
RNA
Cytoplasm
PROTEIN
GENETIC CODE
GENETIC CODE
Principles of Heredity
Chapter 17
Patterns of Heredity

Gregor Mendel
– Punnett Square

Dominant versus Recessive Traits
– Alleles

Autosomal versus Sex linked Traits
– Autosomes versus sex chromsomes
Diploid Cell
Karotype
44 autosomes
2 sex chromosome
Mendelian Genetics
1822-1884
Mendel states

Alternative versions of genes= allele

An organism inherits two genes that segregate independently
Mendel also states

Dominant and recessive alleles
Predict genotype and phenotype by

Punnett Square
First, let’s see how to use the:

The Punnett Square
Punnett Square
curly ears= recessive
“normal” ears=dominant
Cc mates with cc what will the offspring look like?
Look at those ears!
Look at those ears!
Punnett Square: Cc x cc
c
c
C
Cc
Cc
c
cc
cc
Mono-hybrid cross
A single trait
Tall is dominant
Short is recessive
Result of di-hybrid crosses
Cystic Fibrosis: Autosomal Recessive Trait
Autosomal Dominant: Familial
Hypercholesterolemia
(gene dosage effect is observed)

Affects 1:500
cholesterol
Incomplete Dominance

Some traits show
“incomplete dominance”
Sickle cell trait

Incomplete
Dominance
Blood Transfusions & Inheritance of
Blood Types and
Inheritance can sometimes show:

Co-Dominance
Brief Summary

Autosomal traits
–
–
–
–
Hypercholesteremia
Cystic fibrosis
Sickle cell trait
Blood type

Trait are considered either:
–
–
–
–
Dominant
Recessive
Incomplete dominant
Co-dominant
Sex-Linked Traits
COLOR BLINDNESS
Hemophilia
Duchenne’s Muscular Dystrophy

Recessive Sex Linked (X-chromosome)

Males Affected
Sex-influenced Genes

Patterned Baldness
Rogaine
Vasodialor
Propecia
5 alpha R. inhibito
Polygenic Traits
Skin Pigmentation
Multiple genes for melanin: 3-6
 Each has 2 alleles
 Neither allele is dominant


Additional pigmentation genes can
contribute to skin color
Trisomy
Extra “X” Sex Chromosomes

Klinefelter Syndrome
– XXY
– 1:1000 occurrence
– Males
Turner Syndrome
1:10,000
Example of Pedigrees or
Family Trees
Autosomal recessive
Autosomal dominant
Cloning of a whole organism.
Cloning is a process of
providing identical replicates
of DNA.
Hello Dolly!!!!!
How to process begins using a
human cell as an example:
46
23
Somatic Cell
Germ Cell
For ex. Mammary cell
ovum
Overview of the process
46
23
46
discarded
Somatic Cell
Germ Cell
For ex. Mammary cell
ovum
Uncertainty: Does the
offspring represent the
molecular age of the donor or
of a newborn?