Materi Kuliah Dasar2 Genetika Fakultas Pertanian UGM

1. 台大農藝系 遺傳學 601 20000 Chapter 1 slide 1
History of Genetics

2. • Biji bulat warna kuning x Biji kerut warna hijau
AABB x aabb
F1 AaBb
F2 A-B- : bulat kuning = 9
A-bb : bulat hijau = 3
aaB- : kerut kuning = 3
aabb : kerut hijau = 1
X

5. History of Genetics
• People have known about inheritance for a long time.
• --children resemble their parents
• --domestication of animals and plants,
• --selective breeding for good characteristics
• --Sumerian horse breeding records
• --Egyptian data palm breeding
• --Hemophilia

6. Old Ideas
• Despite knowing about inheritance in general, a
number of incorrect ideas had to be generated
and overcome before modern genetics could
arise.
• 1. All life comes from other life. Living organisms
are not spontaneously generated from non-living
material. Big exception: origin of life.
• 2. Species concept: offspring arise only when two
members of the same species mate. Monstrous
hybrids don’t exist.

7. More Old Ideas
• 3. Organisms develop by expressing information
carried in their hereditary material. As opposed to
“preformation”, the idea that in each sperm (or
egg) is a tiny, fully-formed human that merely
grows in size.
• 4. The environment can’t alter the hereditary
material in a directed fashion. There is no
“inheritance of acquired characteristics”.
Mutations are random events.

8. More Old Ideas
5. Male and female parents contribute equally to the
offspring.
• --ancient Greek idea: male plants a “seed” in the
female “garden”.
• --alleged New Guinea belief: sex is not related to
reproduction.

9. Mid 1800’s Discoveries
Three major events in the mid-1800’s led directly to
the development of modern genetics.
1859 Charles Darwin publishes The Origin of
Species, which describes the theory of evolution
by natural selection. This theory requires
heredity to work.
1866 Gregor Mendel publishes Experiments in Plant
Hybridization, which lays out the basic theory of
genetics. It is widely ignored until 1900.
1871 Friedrich Miescher isolates “nucleic acid” from
pus cells.

10. Major Events in the 20th Century
1900 rediscovery of Mendel’s work by Robert Correns, Hugo de Vries,
and Erich von Tschermak .
1902 Archibald Garrod discovers that alkaptonuria, a human disease,
has a genetic basis.
1904 Gregory Bateson discovers linkage between genes. Also coins
the word “genetics”.
1910 Thomas Hunt Morgan proves that genes are located on the
chromosomes (using Drosophila).
1918 R. A. Fisher begins the study of quantitative genetics by
partitioning phenotypic variance into a genetic and an
environmental component.

11. More 20th Century Events
1926 Hermann J. Muller shows that X-rays induce mutations.
1944 Oswald Avery, Colin MacLeod and Maclyn McCarty show that
DNA can transform bacteria, demonstrating that DNA is the
hereditary material.
1953 James Watson and Francis Crick determine the structure of the
DNA molecule, which leads directly to knowledge of how it
replicates
1966 Marshall Nirenberg solves the genetic code, showing that 3 DNA
bases code for one amino acid.
1972 Stanley Cohen and Herbert Boyer combine DNA from two different
species in vitro, then transform it into bacterial cells: first DNA
cloning.
2001 Sequence of the entire human genome is announced.

12. Classical and Modern Genetics
1. Humans have long understood that offspring tend to
resemble parents,
2. and have selectively bred animals and plants for many
centuries.
3. The principles of heredity were first explained by
Mendel in the mid nineteenth century, using defined
crosses of pea plants.

13. Classical and Modern Genetics
2. In the last century, genetics has become an
important biological tool, using mutants to gain an
understanding of specific processes. This work has
included:
a. Analyzing heredity in populations.
b. Analyzing evolutionary processes.
c. Identifying genes that control steps in processes.
d. Mapping genes.
e. Determining products of genes.
f.Analyzing molecular features of genes and regulation of
gene expression.

14. Classical and Modern Genetics
3. Recent important milestones in genetics include:
a. Berg’s construction (1972) of the first recombinant DNA
molecule in vitro.
b. Boyer and Cohen’s first cloning (1973) of a recombinant
DNA molecule.
c. Invention by Mullis (1986) of the polymerase chain reaction
(PCR) to amplify specific DNA sequences

15. Classical and Modern Genetics
4. Completion of genomic sequencing for an increasing
number of organisms has spawned the new field of
genomics. Knowledge of individual genes and their
regulation will be important to basic biological
research, as well as to specific applications such as
medical genetics.
5. Powerful new techniques in genetics raise important
ethical, legal and social issues that will need
thoughtful solutions.

16. DNA, Genes and Chromosomes
1. Genetic material of both eukaryotes and prokaryotes
is DNA (deoxyribonucleic acid). Many viruses also
have DNA
2. DNA has two chains, each made of nucleotides
composed of a deoxyribose sugar, a phosphate
group and a base. The chains form a double helix

17. Peter J. Russell, iGenetics: Copyright © Pearson Education, Inc., publishing as Benjamin Cummings.

18. DNA, Genes and Chromosomes
3. There are four bases in DNA: A (adenine), G
(guanine), C (cytosine) and T (thymine).
a. In RNA, U (uracil) replaces T.
b. The sequence of bases determines the genetic information.
c. Genes are specific sequences of nucleotides that pass traits from
parents to offspring.

19. DNA, Genes and Chromosomes
4. Genetic material in cells is organized into
chromosomes (literally “colored body” because it stains
with biological dyes).
a. Prokaryotes generally have one circular chromosome.
b. Eukaryotes generally have:
i. Linear chromosomes in their nuclei, with different species having
different numbers of chromosomes.
ii. DNA in organelles (e.g., mitochondria and chloroplasts) that is usually a
circular molecule.

21. Eukaryotic and Prokaryotic Chromosome

23. Eucaryote

24. Eucaryote

25. Eucaryote

26. Cell Cycle (1)
The cycle of cell growth,replicationof the genetic material, nuclear and
cytoplasmicdivision.
1. Mitosis (nuclear division)
: corresponding to the separation of
daughter chromosomes and usually
ending with cell division. The events
in this stage of the cell cycle leading
to cell division are prophase,
metaphase, anaphase and telophase.
2. Interphase
: is the time during which both cell
growth and DNA replication occur
in an orderly manner in preparation
for cell division.

27. The eukaryotic cell cycle is divided into 4 major periods:
1. M phase (mitotic phase or mitosis) is the period when cells prepare for and
then undergo cytokinesis. During mitosis the chromosomes are paired and
then divided prior to cell division.
2. G1phase corresponds to the gap in the cell cycle that occurs following
cytokinesis. During G1 cells begin synthesizing all the cellular components
needed in order to generate two identically complimented daughter cells. As a
result the size of cells begins to increase during G1.
3. S phase is the phase of the cell cycle during which the DNA is replicated. This
is the DNA synthesis phase.
4. G2 phase is reached following completion of DNA replication.
The high variability of cell cycle times is due to the variability of the G1
phase of the cycle.
Cell Cycle (2)
The ultimate conclusion of one cell cycle is cytokinesis
resulting in two identical daughter cells.

28. Mitosis

29. Replikasi DNA

30. DNA Replication
(M.S. Meselson and F.W.Stahl, 1957)