VI. Genetics and biotechnology

Question 1

Alleles

Answer 1

different versions of a specific gene

Question 2

Recessive

Answer 2

an allele that has only an effect on the phenotype when present in the homozygous state

Question 3

Dominant

Answer 3

an allele that has the same effect on the phenotype whether it is present in the heterozygous or homozygous state

Question 4

Locus

Answer 4

the place for a specific gene on a DNA-molecule

Question 5

Homozygote

Answer 5

The same alleles

Question 6

Heterozygote

Answer 6

different alleles

Question 7

Genotype

Answer 7

The alleles the organism has (TT, tt, Tt)

Question 8

Phenotype

Answer 8

the characteristics of an organism

Question 9

Where occures Post translational modifications of proteins?

Answer 9

at the peptide terminus of the amino acid chain

Question 10

What important part play Post translational modifications of proteins?

Answer 10

play an important part in modifying the end product of expression and contribute towards biological processes and diseased conditions.

Question 11

Characteristics of eukaryotic genome

Answer 11

• Diploid
• many origins of replication
• has more than one chromosome
• linear chromosomes
• large genome size

Question 12

Characteristics of prokaryotic genome

Answer 12

• haploid
• one origin of replication
• only one chromosome
• circular chromosome
• small genome size

Question 13

What is the theory of operon? (basic)

Answer 13

Genetic regulatory system found in bacteria and their viruses in which genes coding for functionally related proteins are clustered along the DNA. This feature allows protein synthesis to be controlled coordinately in response to the needs of the cell. By providing the means to produce proteins only when and where they are required, the operon allows the cell to conserve energy (which is an important part of an organism’s life strategy).

Question 14

How is gene expression regulated in eukaryotes?

Answer 14

Altering the rate of transcription of the gene. However, eukaryotes supplement transcriptional regulation with several other methods:

• Altering the rate at which RNA transcripts are processed while still within the nucleus. [Discussion of RNA processing]
• Altering the stability of messenger RNA (mRNA) molecules; that is, the rate at which they are degraded.
• Altering the efficiency with which ribosomes translate the mRNA into a polypeptide.

Question 15

Mendel´s law of segregation

Answer 15

states that allele pairs separate or segregate during gamete formation, and randomly unite at fertilization.

Question 16

Mendel´s law of dominance

Answer 16

one from the pair of alleles coding for a particular trait would be expressed whereas the other is unexpressed. The allele expressed for a particular trait is regarded as the dominant whereas the other (which is unexpressed) is considered recessive.

Question 17

Mendel´s law of independent assortment

Answer 17

for every pair of unit factors, each of them would assort independently into the newly formed gametes.

Question 18

What are sex-conjugated genes?

Answer 18

• female can be homozygous or heterozygous with respect to sex-linked genes
• Female carriers for X-linked recessive alleles are always heterozygous since they require a dominant allele and a recessive allele to be carriers.
• They inherit the recessive allele from one parent and the dominate allele from the other.
• For example hemophilia is a sex-linked disease. If a carrier mother and an unaffected father have offspring then the unaffected father will always pass on his dominate allele to his female offspring.
• The carrier mother can either pass on the dominant or recessive allele. If she passes on the recessive allele to her female offspring than the female offspring will be a carrier as well.

Question 19

How is sex heritated in humans?

Answer 19

• From the mother the child always interstates the X chromosome
• From the father the child interstates either the X or the Y chromosome
• Depending on if the child will be a boy or a girl, it will be determines by which chromosome the child gets from the father
• XX will be a female and XY will be a male

Question 20

Variability gained by mutation (origin)

Answer 20

• increase new alleles (more alleles will be formed)

- the rate of change in gene frequency from the mutation process is very low because it is spontaneous

Question 21

Variability gained by recombinants (origin)

Answer 21

• recombinants itself does not produce variation unless alleles are segregating already at different loci; otherwise there is nothing to recombine
• It can be a much faster process of creating variation of recombinants than mutations

Question 22

What is pleiotropy?

Answer 22

the phenomenon of one gene being responsible for or affecting more than one phenotypic characteristic.

Question 23

Where is the point of mutation?

Answer 23

Nucleotide (sequence of the DNA)

Question 24

Insertion (mutation)

Answer 24

An insertion changes the number of DNA bases in a gene by adding a piece of DNA. As a result, the protein made by the gene may not function properly.

Question 25

Deletion (mutation)

Answer 25

A deletion changes the number of DNA bases by removing a piece of DNA. Small deletions may remove one or a few base pairs within a gene, while larger deletions can remove an entire gene or several neighboring genes. The deleted DNA may alter the function of the resulting protein(s).

Question 26

Gene mutation based disease - cystal fibrosis

Answer 26

is an autosomal recessive genetic disorder that mostly affects the lungs, but also the pancreas, liver and intestine. It is caused by a mutation in the gene CFTR (cystic fibrosis trans-membrane conductance regulator), and it’s a deletion of three nucleotides, results in a loss of the amino acid F in the protein.

Question 27

Gene mutation based disease - phenylketonuria

Answer 27

is an autosomal recessive metabolic genetic disorder by homozygous in the gene for the hepatic enzyme PAH (phenylalanine hyroxylase), this enzyme is necessary for metabolize the amino acid Phenylalanine (Phe) to the amino acid tyrosine. When PAH activity is reduced, it is converted into phenylpyruvate, which can be deleted in the urine. This disorder can lead to intellectual disability, seizures.

Question 28

Gene mutation based disease - hemophilia

Answer 28

it is genetic disorder that reduces the ability of the body to control blood clotting which is used to stop bleeding when a blood vessel is broken. It is more likely to occur in males than females, and so it is sex-linked, an x-chromosome disorder. Females have two X chromosome which makes it rare; they can carry this mutation or be affected. But males have only one X which makes it more guaranteed, this happens when the X chromosome is inactivated. Patients have lower blood plasma clotting factor level, means that it prevents the fibrin formation which is necessary to maintain the blood clot.

Question 29

Gene mutation based disease - daltonism

Answer 29

it is colour blondness; because of john Dalton work the condition has been called daltonism. It is the inability to perceive colour differences, under normal lightning conditions. It is sex linked disorder, which affects mostly males because of their one X chromosome. It is not an actual blindness but there is a deficiency of colour vision, most usual cause is in the development of one or more sets of retinal cones that perceive colour in light and transmit that information to the optic nerve, the genes that produce photo pigments are carried on the X chromosome, and if some of these genes are missed or damaged colour blindness will occur.

Question 30

Chromosome-mutation based disease - Down

Answer 30

it is genetic disorder caused by the presence of all or part of a third copy of chromosome 21, where there occur a failure of the 21st chromosome to separate during egg or sperm development during meiosis division. Thus the cell gets 24 chromosomes, when combined with the other parent cell the baby would have 47 chromosomes. It causes intellectual disability and physical growth delays.

Question 31

Chromosome-mutation based disease - Turner

Answer 31

is a chromosomal condition (sex linked) that affects development in females, that becomes evident by about the age of 5, where the ovarian loss its function, it develops normally at first, but the egg cell usually die prematurely. It results when one normal X chromosome is present in female’s cell and the other sex chromosome is missing or structurally altered (missing genetic material), and so it’s called monosomy X, where only one X chromosome is presents instead of two. Many affected girls do not undergo puberty, and some have extra problems comes with this syndrome such as swelling of hands and feet, skeletal abnormalities or kidney problems.

Question 32

Chromosome-mutation based disease - Klinefelter

Answer 32

genetic disorder which there is at least one extra X chromosome to standard human male karyotype, for a total of 47 chromosomes rather than 46 (XXY). It is most common sex chromosome disorder and the second most common condition caused by the presence of extra chromosomes is Down syndrome. This disorder does not show much of symptoms, more frequently, symptoms occur during puberty, such as lack of secondary sexual characters.

Question 33

Coding amino acids in DNA

Answer 33

- The coding for amino acids depend on the sequence of the nucleotides - The nucleotide arrangement determines the codon of the t-rna in translation. - 3 nucleotides form one codon - Depending on in which arrangement the nucleotides are place, different amino acids can be formed when the m-rna sequence is translated.

Question 34

Sex inheritance

Answer 34

The traits we can see (phenotypic) in an organism which are determined by the sex chromosomes (X, Y). The inheritance of a trait (phenotype) that is determined by a gene located on one of the sex chromosomes. Genetic studies of many species have been facilitated by focusing on such traits because of their characteristic patterns of familial transmission and the ability to localize their genes to a specific chromosome. As the ability to map a gene to any of organism’s chromosomes has improved markedly, reliance on the specific pattern of inheritance has waned. Colour blindness and hemophilia are examples of sex linkage.

Question 35

Chromosome and characteristics of diploid organism

Answer 35

Chromosomes are the DNA sequences, where DNA and histones are condensed. In karyotype which is the term used for the complete set of chromosomes in an organism, describes the number of chromosomes, what they look like, attention is paid to their length and the position of the centromeres. The basic number of chromosomes is the somatic cells which is called somatic number (diploid) that contain 2n = 46, and the sex cells (haploid) n = 23. In the normal diploid organisms, autosomal chromosomes have two copies may or may not be sex chromosomes, but haploid cells have single copies.

Question 36

State the phases of the cell cycle

Answer 36

Interphase G1 phase S phase G2 phase

Question 37

What occurs in interphase

Answer 37

it is a very active period, the cell carries out many biochemical reactions and growth. DNA is uncoild into chromosomes and the genes are transcribed, allowing protein synthensis that is needed for growth. Also increase in number of molecules inside the cell ex. Mitochondria.

Question 38

What happens in G1 of the cell cycle

Answer 38

period of growth, DNA transcription and protein synthesis

Question 39

What happens in S-phase of the cell cycle

Answer 39

DNA replication

Question 40

What happens in G2 of the cell cycle

Answer 40

period for the cell to prepare for the cell division

Question 41

Describe the DNA organization in genome

Answer 41

Genome is the term used to describe the total genetic information in human cells. This information is encoded as DNA sequences within the 23 chromosome pairs in cell nuclei. DNA is composed of arrangement of four nucleotides in specific pattern. These nucleotides present as a function of their order. The genome of all organisms is composed of one to multiple numbers of DNA molecules. Human genome include both protein coding DNA genes and non-coding.

Question 42

Which types of RNA are present in cells

Answer 42

mRNA tRNA rRNA

Question 43

Double helix and its role in DNA replication

Answer 43

Double helix is double stranded structure, with both strands coiled together to form double helix. Each strand is a chain of four types of nucleotides that contain deoxyribose, sugar and nucleobase. These nucleotides form phosphate-deoxyribose backbone, which are covalently bonded. The nucleobases are are bonded by hydrogen bonds to form base pairing which called complementary base pairing. The double helix has two ends of a single strand called 3’ and 5’. Double helix contain of two DNA strands which contain genetic codes, that during replication, it results in two perfect copies of the original DNA. If one strand is messed up in replication, there is still another perfect copy on the other side because DNA replication is semi conservative.

Question 44

Structure of nucleotides

Answer 44

Nucleobases adenine A, cytosine C, guanine G, thymine T. A and G are purine bases, T and T are pyrimidines.