Medical Biology - Genetics

Medical Biology - Genetics

Question


Make a comparison between chromosome of prokaryotic and eukaryotic cells
The answer
The chromosome
The German embryologist Walter Fleming was describing the chromosome during follow-up the cell division in Salamander larvae in 1882. The nucleus contains genetic information in the form of chromosome, highly folded ribbon-like consisted of deoxyribonucleic acid (DNA) and a class of proteins called histones. Gnomic DNA is tightly and orderly packed in a process called DNA condensation to fit the small available volumes of cell.
Shape of chromosome
Structure of chromosome
Chromosome: is a thread – like structure composed of chromatin that carries a large numbers of genes which determine all the individual characters.
Chromatin: is a DNA- protein (histone) complex found in eukaryotic chromosomes.
Histone: a group of water soluble proteins found in association with the DNA chromosomes, they believed to be involved in the condensation and coiling of chromosome during cell division .It is found in eukaryotic cell and deficient in bacteria.
Centromere : it is a constriction area that linked two chromatid in the chromosome this part of chromosome free of genes.

Structure of chromosome
Question


Why called on both DNA and RNA nucleic acid and polymeric?
The answer


Question - Make differences between DNA and RNA
Watson – Crick?s double helical model of DNA characters
1- The DNA molecule consist of two polynucleotide chains wound around each other in a right – handed double helix ( clockwise fashion) .
2- The external diameter of the helix is 2 nm.
3- The two chains are antiparallel that is , the two strands are oriented in opposite directions , with one strand oriented in the 5? to 3? way , while the other strand oriented 3? to 5? , antiparallel means that the head of one chain is against the tail of the other chain .
Watson – Crick?s double helical model of DNA characters
4-The sugar – phosphate backbones are on the outsides of the double helix, while the bases oriented toward the central axis.
5-The two sugar – phosphate backbones of the double helix are not equally spaced along the helical axis , this result in grooves of unequal size between the backbones called the major ( wider ) groove and the minor ( narrower ) groove, both of these grooves are large enough to allow protein molecules to make contact with bases .
Watson – Crick?s double helical model of DNA characters
Watson – Crick?s double helical model of DNA characters
6-The bases of opposite strands are bonded together by hydrogen bonds, which are relatively weak chemical bonds. The specific pairings observed are A with T (two hydrogen bonds) and G with C (three hydrogen bonds).
The hydrogen bonds make it relatively easy to separate the two strands of the DNA. The specific A – T and G – C pairs are called complementary base pairs , so the nucleotide sequence in one stand may compatible with nucleotide sequence
of the other
Question

If one chain of DNA strand has the sequence 5?- TATTCCGA- 3? then the opposite antiparallel chain must bear?
The answer - DNA strands

First strand 5?- TATTCCGA - 3?
Second strand 3?- ATAAGGCT- 5? .


Central Dogma of molecular biology
Replication process

Transmission of genetic information in genes is achieved via complementary base pairing in a process called transcription through attraction between the DNA and the messenger RNA nucleotides; mRNA is then exported from the nucleus to the cytoplasm, where it is bound to ribosome.
The order of amino acids is determined by 3 adjacent nucleotides (triplets) on strand mRNA is called codon and translated into its corresponding protein form with the help of transfer RNA (tRNA) is a small RNA chain of about 80
nucleotides carry 3 adjacent nucleotides (triplets) called anticodon that transfers a specific amino acid to a growing polypeptide chain at ribosomal site of protein synthesis during translation. There are 64 codons and only 20 amino acids the code is redundant.
Translation process
Mendel s first laws in genetic
Mendel s second laws in genetic
Question of lecture

Who responsible on replication, transcription, and translation processes in eukaryotic cells
The answer

The nucleoplasm proteins in nucleus was responsible on replication and transcription processes but the translation process occur in cytoplasm in ribosome.



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