Bio 201 Fall 2008 True lect 3v2r

Bio 201 Fall 2008 True lect 3v2r - Darwin and inheritance...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Darwin and inheritance • Darwin was unaware of Mendel’s work • Chromosome theory of inheritance was not yet developed • Meiosis was not yet understood • Reconciling Darwinian natural selection with new genetic knowledge was one of the main pursuits of early 20th century biology
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chromosomes • First discovered in plants and worms in 1842, using microscopy on tissue preparations stained with various dyes • Later named “chromosomes” (color bodies) Drosophila larval salivary gland chromosomes Human mitotic chromosomes
Background image of page 2
Chromosomes • Linear molecule of DNA – Normally not visible (interphase cells) • Visible in: – Mitosis (various cell types) and meiosis • Highly condensed and packaged with proteins – In some tissues when chromosomes are massively over-replicated (many thousands of copies aligned side-by-side) • Why would cells do this? Drosophila larval salivary gland chromosomes Human mitotic chromosomes
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chromosome theory of inheritance Theory: chromosomes are linear arrangements of genes - combined cell biology and genetic data Established in the early 20th century from many observations in several organisms – Peas • William Bateson; 1st to the term “genetics” • Hugo DeVries Drosophila • Thomas Hunt Morgan, Calvin Bridges – Salamander ( Batrachoseps attenuatus) • F.A. Janssens Drosophila larval salivary gland chromosomes Human mitotic chromosomes California slender salamander Batrachoseps attenuatus
Background image of page 4
Mitosis • Mitosis: DNA replication/cell division during growth and development (in multicellular plants and animals) • Takes place in all somatic tissues • One diploid (2N) cell replicates its chromosomes (“4N”) and then divides once, resulting in two diploid (2N) daughter cells that are exact copies of the original cell [N refers to the haploid chromosome number. N for humans = 23, N for Drosophila melanogaster = 4]
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Mitosis in this example N=2 chromosomes Pre-mitotic cell 2N chromosome replication (S-phase: synthesis) 4N Mitotic metaphase Daughter cells 2N 2N Chromosomes from mother: red Chomosomes from father: blue
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/14/2009 for the course BIO 201 taught by Professor True during the Fall '08 term at SUNY Stony Brook.

Page1 / 30

Bio 201 Fall 2008 True lect 3v2r - Darwin and inheritance...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online