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?