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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 Cell
23 pairs or 46 chromosomes
44 autosomes
2 sex chromosome
How do all of our non-reproductive cells
divide & keep 46 chromosomes?
Somatic Cell Division
Mitosis
prophase
anaphase
metaphase
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
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
http://learn.genetics.utah.edu/content/begin/dna/tra
nscribe/
Nirenberg and Khorana, were awarded the
1968 Nobel Prize in Physiology or Medicine.
GENETIC CODE
http://bcs.whfreeman.com/thelifewire/cont
ent/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 Cell
Karotype
44 autosomes
2 sex chromosome
Gregor Mendel (Mendelian genetics) states
1822-1884
•
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
Now let’s look at how to construct and use
a 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  Trait are considered either:
–
–
–
–
Hypercholesteremia
Cystic fibrosis
Sickle cell trait
Blood type
–
–
–
–
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
Propecia
Polygenic Traits
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 of a whole organism: Reproductive Cloning
SHEEP CELLS
54
Somatic Cell
For ex. Mammary cell
27
Germ Cell
ovum
How to process begins:
54
54
27
discarded
Somatic Cell
For ex. Mammary cell
Germ Cell
ovum
Uncertainty: Does the offspring
represent the molecular age of the
donor or of a newborn?
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