Biology 321 Genetics

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Biology 321 - Genetics
Lecturing
Dr. Mary Anne Pultz x3640 Dr.
Jeff Young
T.A.s Jennifer Haynes Elizabeth Snyder
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Some Course Mechanics
Todays lecture will be posted under
Biology/ Courses/Dr. Youngs courses. Later, on
Blackboard Quizzes will be announced, first
quiz will be all-or-nothing meiosis quiz Tues Jan
13. Friday sessions are an integral part of the
course, Not an optional review/problems
session We want you to be involved in asking
questions, volunteering answers to questions
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Reading assignments
For Thurs, Jan 8, Chaps 1,2 For Fri, Jan 9,
Through Chap 3.3, and 3.6
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Genetics is fundamental
for all study of Biology, since genes control
the characteristics of organisms, ranging from
human health to populations of organisms in
ecosystems
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Historical Overview - Classical Genetics
Since antiquity,
blending
common sense
Mendel
Abstract, symbolic
not blending
Published 1866
Related physical chromosomes and Mendels ideas
Sutton, Boveri
1902
1950s
Structure of DNA
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Our Approach hereChromosomes first,then Mendel
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Focus on Meiosis
Meiosis is the type of cell division happening
in sperm and egg cells (ova)
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Focus on Meiosis

• and its relationship to
• information content what is a genome?
• macromolecules of chromosomes
• mitosis - what goes where, when?
• life cycles
• genetics of Mendel and beyond

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a) What is a genome?
One complete set of instructions to make a
given organism, encoded in DNA as AATAGCGCCAT
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a) What is a genome?
One complete set of instructions, mostly about
how to make proteins, which are the major doers
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a) What is a genome?
One complete set of instructions, mostly about
how to make proteins, which are the major doers
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a) What is a genome?
One complete set of instructions, mostly about
how to make proteins, which are the major
doers We can think about an encyclopedia
analogy
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a) What is a genome?
In genomes, (unlike encyclopedias) Some of DNA
sequence codes for proteins Some is spacer or
junk (the proportion varies) Some is other
(well get to that later)
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a) What is a genome?
The whole genome of an organism could, In theory
be one long DNA molecule one chromosome But
most organisms (except bacteria) dont do it
this way
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a) What is a genome?
The genome of any given eukaryotic species is
usually chopped up into n DNA molecules n
chromosomes per genome where n is a number that
applies to all normal members of the species
human n 23, pea n 7, Drosophila n 4
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Diagram on the blackboard
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a) What is a genome?
The DNA content per genome and number of genes
also varies from species to species
12 Mb
Yeast
n 16
6,500 genes
14,000 genes
170 Mb
n 4
Drosophila
n 23
3,000 Mb
35,000 genes
Human
n 5
Arabadopsis
125 Mb
25,000 genes
Tomato
Mb megabases 1 million bases
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a) What is a genome?
Diploid organisms inherit one whole genome from
each parent, a different edition from each
parent
Peas, humans, fruit flies, Arabadopsis, maize are
diploid organisms
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a) What is a genome?
Diploid organisms have TWO VERSIONS of each
gene in body cells (somatic, sporophyte
cells) In contrast there is ONE VERSION of each
gene in gametes (sperm, ova)
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a) What is a genome?
Sets vs. pairs of chromosomes (diagram on
blackboard)
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a) What is a genome?
Parting thought Now we hope you will be able to
look at the sticks in meiosis/mitosis and
think about their information content
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Meiosis
Another parting thought The problem for Meiosis
is What is the strategy to get from two copies
of the genome to one copy of the genome.