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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 Cell23 pairs or 46 chromosomes
44 autosomes
2 sex chromosomes
How do all of our non-reproductive cells divide & keep 46 chromosomes?
Somatic Cell Division
Mitosis
prophasemetaphase
anaphase telophase
The cell cycle
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
http://highered.mcgraw-hill.com/olc/dl/120074/bio17.swf
http://highered.mcgraw-hill.com/olc/dl/120074/bio19.swf
Mitosis versus meisosis
Meiosis I and II
Animation LINKS
MEISOSIS and FERTILZATION
23 chromosomes
23 + 23 =46
Ch. 18 concept: How does DNA affect your phenotype?
Central Dogma
DNARNA
Protein
The next 6 slides will refer to material found in chapter 18.
DNA
RNA
PROTEIN
Cytoplasm
Nucleus
GENETIC CODE http://learn.genetics.utah.edu/content/begin/dna/transcribe/
Nirenberg and Khorana, were awarded the 1968 Nobel Prize in Physiology or Medicine.
GENETIC CODE http://bcs.whfreeman.com/thelifewire/content/chp12/1202001.html
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 CellKarotype
44 autosomes
2 sex chromosomes
Gregor Mendel (Mendelian genetics) states
• Alternative versions of genes= allele
• An organism inherits two genes that segregate independently
1822-1884
Mendel also states
• Dominant and recessive alleles
Predict genotype and phenotype by
• Punnett Square
Now let’s look at how to construct and use a Punnett Square:
Punnett Squarecurly 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
CCcc CCcc
cccc cccc
C
c
c c
Mono-hybrid crossA single trait
Tall is dominantShort 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 SummaryBrief Summary
Autosomal traitsAutosomal traits– HypercholesteremiaHypercholesteremia– Cystic fibrosisCystic fibrosis– Sickle cell traitSickle cell trait– Blood typeBlood type
Trait are considered Trait are considered either:either:– DominantDominant– RecessiveRecessive– Incomplete dominantIncomplete dominant– Co-dominantCo-dominant
Sex-Linked Traits
COLOR BLINDNESS
Hemophilia
Duchenne’s Muscular Dystrophy
Recessive Sex Linked (X-chromosome)
Males Affected
Sex-influenced Genes
• Patterned Baldness
Propecia Rogaine
Polygenic Traits
Trisomy
Extra “X” Sex Chromosomes
• Klinefelter Syndrome– XXY
– 1:1000 occurrence
– Males
Turner Syndrome
1:10,000
Example of Pedigrees or Example of Pedigrees or Family TreesFamily Trees
Autosomal recessive
Autosomal dominant
Cloning of a whole organism.
Cloning of a whole organism: Reproductive Cloning
Somatic Cell Germ Cell
For ex. Mammary cell ovum
SHEEP CELLS
54 27
Somatic Cell Germ Cell
For ex. Mammary cell ovum
How to process begins:
542754
discarded
Uncertainty: Does the offspring represent the molecular age of the
donor or of a newborn?