Asist. Prof. Nuket Bilgen, DVM, PhD.
Basic genetic
terms
Theories of inheritance
• Pythagoras
• Empedocles
• Aristotle
• Pangenezis and Germ plasm
• De Vries mutation
• Mendel
• Chromosomal basis of heredity
Chromosomal Basis of Heredity
• What do you know about chromosomes?
• It has been seen in the tradescantia plant by Hofmeister,
• The name Chromosome was given by Waldeyer.
Chromosomal Basis of Heredity
• “I would like to permit myself to suggest that the specific technical term chromosomes is
attributed to those things which Boveri titled chromatic elements, on which one of the most important parts of caryogenesis, Flemming’s longitudinal splitting, is performed. They are of such importance that a particularly short name appears desirable. If the term which I suggested can be practicably used, then it will become
established; if not, it will vanish into oblivion”
Chromosomal Basis of Heredity
• The continuity of life depends on the continuity of the chromosomes.
• The shapes may be different in all living things, but the same chromosomes are similar in the same species.
• For example, the 5th chromosome is the same in all humans but in humans the
chromosomes 5 and 22 are different.
Chromosomal Basis of Heredity
• Chromosome numbers and genes are in direct proportion?
-There is no relationship between chromosome number and development level.
• Big chromosomes has more genes than small ones?
- There is no relationship between the size of the chromosome and the number of genes carried
Chromosomal Basis of Heredity
• Ascaris megalocephala lowest chromosome number 2n=2
• Drosophila melanogaster: 2n=8
• Human: 2n=36
• Goat: 2n=60
• Fern: 2n=500
Chromosomal Basis of Heredity
• Somatic cell: body cells containing a pair of chromosomes. diploid
• Germinative cells: sex cells, adult gametes do not have chromosomes. haploid
• The number of chromosomes in the parthenogenetically proliferating male animals are n, female animals are 2n.
• What is Endomitosis?
Chromosomal Basis of Heredity
• Differences between chromosome and chromatin
Chromosome structure
Telocentric, Acrocentric, Submetacentric and Metasentric
• Human chromosomes are typical eukaryotic chromosomes.
• Some organisms might have extraordinary chromosome types.
–Micro-chromosomes , –Giant chromosomes ,
–Holocentrik chromosomes
• Micro-chromosomes : short buut has the majority of the genes in the genome.
Chicken genome has 6 macro- chromosomes (25% genes) 33 microchromosomes (75% genes)
• Giant chromosomes: saliva gland of some flies and some lipid tissues have giant
chromosomed cells.
• Holocentrik chromosomes: multiple centromeres are found in this type.
C. elegans.
• Cell without a centromer can not join to the cell division.
• Telomeres are located at the ends of the chromosomes and prevent the adhesion of the ends of linear chromosomes.
• During cell division DNA got shortened from telomeres.
Telomeres,
2009 Nobel
• Genes are parts of chromosomes.
• Mitosis is the nuclear division that results in two daughter nuclei whose genetic material is
identical with that of the original nucleus.
• Meiosis is the nuclear division by which a reproductive cell with two equivalent
chromosome sets divides twice to produce four meiotic products, each of which has only one set of chromosomes.
• Mendel’s laws of equal segregation and independent assortment are based on the separation in meiosis of members of each
chromosome pair and on the independent meiotic behavior of different chromosome pairs.
• Chromosomes can be identified microscopically by using various visible landmarks. A chromosome
contains a single, long DNA molecule. DNA winds around protein spools, and the spooled unit then coils, loops, and supercoils, forming a
chromosome. A large proportion of eukaryotic DNA is present in multiple copies. Most of the multiple- copy DNA has no known function.
HOMEWORK
• What are Abiogenesis and Biogenesis
?• nbilgen@ankara.edu.tr
Life, living…
• Having a special chemical sequence;
– Living creatures have a special shape of this chemical bond sequence, while the inanimate has a
combination of chemical bonds.
• Having cellular sequencing;
• Growth
• Energy use,
• Harmony with the environment
• Reproductive
• Adaptation and variation inheritance
• Movement
1665 Robert Hooke
The origins of the theory of the cell
• 1665 Robert Hooke observed the cork cells with their microscope in the form of peripheries and voids and gave them the name of cell (cellula).
• 1831 Robert Borwn discovered the Nucleus,
• 1839 Purkinje gave the name of the liquid protoplasm that filled the wall.
Theory of cell (Wirchow)
1) Cell is the structural and functional basic unit of living organisms. All known living beings are
composed of more or one cell in one place.
2) All cells come into being by dividing an existing cell.
3) All metabolic and biochemical energy flows occur within the cells.
4) Cells inherit the hereditary information (nucleic acids and DNA in the cell) from one cell to another through cell division.
5) All the cells in organisms belonging to similar
species have basically the same chemical structure.
What is cell?
Trees in a forest, fish in a river, lemurs in the jungle, worms in the soil
— all these plants and animals are made of the building blocks we call cells. Like these examples, many living things consist of vast
numbers of cells working in concert with one another.
Other forms of life, however, are made of only a single cell, such as the many species of bacteria and protozoa.
Cell
Cells, whether living on their own or as part of a multicellular organism, are usually too small to be seen without a light microscope.
•Cells are basically the same, but may look very different from their specialized tasks.
Cell
Cells are the smallest structural and functional unit of living organisms and are divided
according to their level of development:
1-Prokaryote Cells: The nucleus is absent and the genetic material is scattered in the
protoplasm.
The cell membrane surrounds the protoplasm.
The protoplasm is membrane organelle free.
Only ribosome is found in prokaryotes.
Bacteria, blue-green algae are prokaryotic cells.
Prokaryote
protoplasm: Intracellular fluid.
All elements floats in it.
Flagella: It helps the bacterium to move and helps to feed.
Pili: it plays a role in gene transfer.
Capsule: A third coat that increases the chances of
survival of bacteria in extreme cold and hot.
Prokaryote
• Chlorophyll: It is found in photosynthetic bacteria. It allows the bacteria to produce food and oxygen.
• Nucleoid: A region in the nucleus where the genetic material is present in the
prokaryotes, but not surrounded by the nucleus membrane.
2- Eukaryotic Cells: This type of cells is
surrounded by the nucleus membrane. The
organelles have membrane, the cell membrane and the cytoplasm. For example, fungi,
animals, plants are eukaryotic..
Prokaryotic Eukaryotic Difference
eukaryotic cell structure diagram
The nucleus
• the nucleus (meaning kernel or seed) is a membrane-enclosed organelle found in eukaryotic cells.
• Eukaryotes usually have a single nucleus,
• mammalian red blood cells have no nuclei,
• osteoclasts have many.
The nucleolus
• A discrete densely stained structure found in the nucleus.
• It is not surrounded by a membrane, and is sometimes called a suborganelle.
• It forms around tandem repeats of rDNA, DNA coding for ribosomal RNA (rRNA).
Ribosomes
• All compounds with a protein structure are synthesized in this organelle according to RNA types.
• Ribosomes are universal.
• Artificial DNA?
Proteins Amino Acids Ribosomes Word Letter Typewriter
Mitochondria
• Mitochondria act as the power plants of the cell, are surrounded by two membranes, and have their own genome.
• They can divide independently of the cell in which they reside, meaning mitochondrial replication is not
coupled to cell division.
• Some of these features are holdovers from the ancient ancestors of mitochondria, which were likely free-living prokaryotes.
endomembrane system
• Endoplasmic Reticulum material transport
•
• Golgi Apparatus: protein synthesis
• Lysosomes
