BIOLOGY2 #1

THE DNA and GENETIC INFORMATION

Nucleic acids are complex molecules containing C, H, O, P and N elements. They are composed of polynucleotide chains.

MODERN GENETICS: RECOMBINANT DNA TECHNOLOGY

- RECOMBINANT DNA TECHNOLOGY
- NATURAL DNA RECOMBINATION

RECOMBINANT DNA TECHNOLOGY

refers to various techniques and procedures used in gene manipulation.

NATURAL DNA RECOMBINATION

the recombination occurs randomly during the crossing-over of homologous chromosomes during meiosis 1, during fertilization when 2 gametes fuse, or even through mutation.

DNA recombination in natural and technology

is being used in improving production of agricultural products, forensics, pharmaceuticals and medicine.

GENETIC ENGINEERING

It involves the use of molecular techniques to modify the traits of target organisms. These are often referred to as transgenic organisms or genetically modified organisms (GMO)

GENETIC ENGINEERING

- also known as genetic modification.
- its achieved by adding a specific gene or genes or removing undesirable gene, to produce a desirable phenotype. The gene can be from the same species or different organism

CLASSICAL BREEDING

It focuses on the mating of organisms with desirable qualities. It relies heavily on natural occurring life cycle of organisms and homologous recombination to remove undesirable traits.

CLASSICAL BREEDING

- Interbreeding can only be carried out with closely or distantly related organisms

CLASSICAL BREEDING

- It is time-consuming as breeding needs series of crossing and self-fertilization to be able to attain desired trait

TOOLS USED IN RECOMBINANT DNA TECHNOLOGY

- TARGET DNA
- RESTRICTION ENZYMES
- DNA CLONING VECTORS
- HOST CELL
- MODIFYING ENZYMES

TARGET DNA

This is gene of interest, the gene sequence that codes for the desired trait

RESTRICTION ENZYMES

These enzymes identify specific base sequence and cut the DNA at a specific point between 2 nucleotides.

DNA CLONING VECTORS

These are DNA materials used to carry the target DNA to be transferred

HOST CELL

a cell that is able to accept the target DNA to multiply or replicate it.
- must be able to maintain the structure of the recombinant DNA all throughout generation

MODIFYING ENZYMES

These are enzymes involved in degradation, synthesis and alteration of the nucleic acids.

METHODS OF GENE CLONING FOR DNA RECOMBINATION

The process of gene cloning involves a complex process mostly varied but almost similar with the concepts of natural processes of DNA replication and protein synthesis

4 stage of gene cloning

1. isolation of target gene
2. insertion of target gene into the vector
3. introduction of vector the host cell
4. amplification off the target gene by host cell

ISOLATION OF TARGET GENE

cutting the gene from original chromosome or producing a complementary DNA by replicating the target gene.

INSERTION OF TARGET GENE INTO THE VECTOR

The target gene is inserted into the vectors resulting to recombinant DNAs

3rd stage of gene cloning

INTRODUCTION OF VECTOR THE HOST CELL

AMPLIFICATION OF THE TARGET GENE BY THE HOST CELL

The host cells are allowed to reproduce to produce multiple copies of the target genes

EXAMPLES OF TRANSGENIC ORGANISMS

- BT corn
- golden rice
- transgenic atlantic salmon
- transgenic ruminants
- human insulin producing e. coli
- genetically modified pseudomonas bacteria

CLASSICAL GENETICS: MENDELIAN GENETICS

- gene
- allele
- locus
- dominant
- recessive
- homozygote
- heterozygote
- genotype
- phenotype
- test cross
- partial generation

GENE

- the sequence of DNA that codes for a specific trait.
ex: The DNA sequence that codes for the color of the eyes. These are represented by any letter in genetic problems

GENE

- basic unit of information that determines the inherited characters

ALLELE

the alternative forms of genes (minimum of 2)
EX; the color of the eyes differ among individuals. Blue and brown are the most common.

LOCUS

the location of the genes in the chromosomes

DOMINANT

the allele that is expressed in case more than one allele is present. These are represented by UPPERCASE letters.

RECESSIVE

allele that is not expressed in case more than one allele is present. These are represented by lowercase letters

HOMOZYGOTE

a combination of similar alleles. EX: BB or bb

HETEROZYGOTE

combination of different alleles

GENOTYPE

the combination of genes represented by letters. They are always write in pairs. EX: bb, BB, Bb

GENOTYPE

- at each locus (except for sex chromosomes) there are 2 genes. these constitute the individuals genotype at the locus

PHENOTYPE

the appearance of specified genotype.

PHENOCOPY

- trait that is expressed due to specific environmental conditions
ex: having hair that is dyed of a different color and is not due to the genotype)

TEST CROSS

these are used to determine if an individual with dominant trait is homozygote or heterozygote. The individual with unknown genotype is crossed to a homozygous recessive

PARENTAL GENERATION (P)

the first genotypes that are crossed; FIRST FILIAL GENERATION (f1)- generation after P; SECOND FILIAL GENERATION (f2)- generation after f1

MENDELIAN LAW

- law of segregation
- law of independent assortment
- dominance

GREGOR MENDEL

father of genetics
an austrian monk, known as the father of genetic due to his discoveries on the passing of traits from 1 generation to another.

GREGOR MENDEL

His famous garden peas experiment revealed the concepts of heredity though during his time, there are no concepts of nucleic acids and chromosomes

LAW OF SEGREGATION

Alleles coming from the parents combine during fertilization. Therefore, there are two alleles per trait in an individual.

LAW OF SEGREGATION

However, during gamete formation (Meiosis), these pair of alleles will separate or segregate. (Take note, in meiosis, diploid cells will produce haploid daughter cells).

LAW OF SEGREGATION

Therefore, when they are passed to the next generation, either but not both of the alleles are passed to one offspring. Let's explain this using monohybrid crosses or crosses involving one trait only.

GENETICS

study of hereditary terminologies

PEDIGREE

- making use of diagram knowing the ancestral relationships and transmission of genetic traits over several generations in a family

PROBAND

the individual in the pedigree that led to the construction of the pedigree

GENOME

collection of genetic info

CHROMOSOME

storage unit of genes

how many somatic cells?

44

how many sex cells

2

how many chromosomes

46

2 TYPES OF NUCLEIC ACIDS:

DNA and RNA

DNA

responsible for storing information that serves as basis for synthesis of proteins that in turn control all reaction and formation of structures.

DNA

- nucleic acid that contains the genetic instruction specifying the biological development of all cellular forms of life

RNA

plays several role in the actual building of proteins

GENETIC ENGINEERING

- Sometimes, the desired trait is attained faster than classical breeding.

SURVIIVAL OF THE FITTEST

- adapt
- reproduce
- thrive