Najaf bio 4 4 (2)
Published on: Mar 3, 2016
Transcripts - Najaf bio 4 4 (2)
Najaf, Henry, Shugofa, Kelly4.1Chromosomes are bundles of long strands of DNA.A human cell contain enough DNA to stretch for nearly two metres.Chromosomes always come in pairs in eukaryotes.Humans have 46 chromosomes in 23 pairs.Prokaryotes have only one chromosome, and the DNA is not associated with proteins.GenesA gene is a heritable factor, meaning passing on from parent to offspring, that controls a specificcharacteristic.Variations of a gene are called alleles.An allele is one specific form of a gene, differing from other alleles by one or a few bases.MutationsA mutation is a random, rare change in genetic material.One type involves a change of a sequence of bases in DNA.Base substitution mutationIn humans, a mutation is sometimes found in the gene which creates haemoglobin for red bloodcells. This mutation gives a different shape to the haemoglobin molecule.The difference leads to red blood cells which look very different from the usual flattened diskpinched in the middle. The condition which results from this mutation is therefore called sicklecell anaemia.The kind of mutation which causes sickle cell anaemia is called a case substitution mutation. Onebase is substituted for another so the codon GAG becomes GTG.Sickle cell anaemiaSymptoms are weakness, fatigue, and shortness of breath.People affected by sickle cell anaemia have a risk of passing the mutated gene to their offspring.
Henry, Najaf, Kelly, Shugufa4.2 Genotype-The combination of alleles of a gene carried by an organism Phenotype-The expression of alleles of a gene carried by an organism Centromeres join chromatids together Alleles a are different versions of a gene, dominant and recessive Humans have 46 chromosomes Crossing over occurs in prophase 1 TT= Tall Tt= Short What percentage of the plants will be homozygous recessive short? Pedigree charts can be used to trace family histories and deduce genotypes and risk in the case of inherited gene-related disorders Antibodies (immunoglobulins) are specific to antigens. Sex genes are not homologous eukaryotic chromosomes are made of DNA and proteins meiosis is A reduction division of a diploid nucleus to form 4 haploid nuclei homologous chromosomes are Chromosomes with the same gene loci in the same sequence
Najaf, Henry, Kelly, Shogufa4.3Meiosis Meiosis is a form of cell division which results in gametes (sex cells). Cells which contain half the chromosome number are called haploid cells. Cells with the full chromosome number are called diploid cells. In a diploid human cell, the 46 chromosomes can be grouped into 23 pairs of chromosomes called homologous chromosomes. One of the characteristics which distinguishes meiosis from mitosis is that during the first step, called prophase I, there is an exchange of genetic material between non-sister chromatids in a process called crossing over.Prophase I1. Chromosomes become visible2. Homologous chromosomes pair up3. Crossing over occurs4. Spindle fibers formMetaphase I1. Homologous chromosomes line up across equator2. Nuclear membrane disintegratesAnaphase I1. Spindle fibers attach to chromosomes and pull them to opposite polesTelophase I1. Spindle fibers disintegrate2. Chromosomes uncoil and new nuclear membranes form- Cytokinesis happens: cell splits into two separate cells.- Meiosis II takes place in order to separate the sister chromatids.Prophase II1. DNA condenses into visible chromosomes again2. New spindle fibers formMetaphase II
1. Nuclear membranes disintegrates2. The individual chromosomes line up along the equator3. Spindle fibers from opposite poles attach to each of the sister chromatids at the centromeresAnaphase II1. Centromeres of each chromosome split, releasing each sister chromatid as an individual chromosome2. Spindle fibers pull individual chromatids to opposite ends of the cell3. Because of random orientation, the chromatids could be pulled towards either of the newly forming daughter cellsTelophase II1. Chromosomes unwind their strands of DNA2. Nuclear envelopes form around the four haploid cellsDown’s Syndrome In case of Down’s Syndrome, non-disjunction happens in the 21st pair of chromosomes: thechild receives 3 instead of 2. Such an anomaly is called a trisomy and Down’s Syndrome is alsoreferred to as trisomy 21.Karyotypes1. The cells are stained and prepared ona glass slide to see their chromosomes under a light microscope.2. Photomicrograph images are obtained of the chromosomes during mitotic metaphase.3. The images are cut out and separated, a process which can be done using scissors or using a computer.4. The images of each pair chromosomes are placed in order by size and the position of their centromeres.
Henry, Najaf, Kelly, Shugufa4.3 Genotype-The combination of alleles of a gene carried by an organism Phenotype-The expression of alleles of a gene carried by an organism Centromeres join chromatids together Alleles a are different versions of a gene, dominant and recessive Humans have 46 chromosomes Crossing over occurs in prophase 1 TT= Tall Tt= Short What percentage of the plants will be homozygous recessive short? Pedigree charts can be used to trace family histories and deduce genotypes and risk in the case of inherited gene-related disorders Antibodies (immunoglobulins) are specific to antigens. Sex genes are not homologous eukaryotic chromosomes are made of DNA and proteins meiosis is A reduction division of a diploid nucleus to form 4 haploid nuclei homologous chromosomes are Chromosomes with the same gene loci in the same sequence
Najaf, Henry, Shugofa, Kelly4.4 Genetic Engineering and BiotechnologyPolymerase Chain Reaction1. Polmerser chain reaction- the polymerase chain reaction is a method formaking copies of a specific segment of DNA, starting with a very small amount2. The technique is used to identify specific micrograms from a small amount ofDNA and to identify persons involved in crimes from DNA on cigarites or in singlehair follicles.3. The DNA to be amplified is mixed with deoxyribonuclitides, a thermal stableDNA polymerase called Taq polymerase and DNA primers4. The mixture is heated to break the hydrogen bonds in the DNA, forming singlestranded molecules. The mixture is then cooled sufficiently to allow the DNAprimers to anneal to each end of the segment to be copied.5. Taq polmerser then synthesis the complementary strand of DNA, using theprimer as the starting point.
6. The temperature is raised again to separate then lowered sufficiently to allowperimeters to attach7. This processes is repeated until enough DNA has been produced to identified.DNA Profiling- is the process of matching an unknown sample of DNA with aknown sample to see if they correspond.Applications- DNA profiling can be used in paternity suits when the identity ofsomeone’s biological father must be known.Human Genome Project- hoped to determine the order of all bases A, T, C, and Gin human DNA. In 2003, the project announced that it had succeeded in achievingits goal. The Human Genome Project has pushed forwards medical andpharmacological research.
Cutting, copying, and pasting genesThe ‘scissors used for cutting base ’Restriction enzymes called endonucleases findand recognize a specific sequence of base pairs along the DNA molecule. Theendonucleases cut DNA at specified points. If both the beginning and the end of agene are cut, the gene is released and can be removed from the donor organism.Copying DNA (DNA cloning) Host cell is needed- Escherichia coli. Some DNA can be found in plasmids (small circles of extra copies of DNA floating in the cell’s cytoplasm. To copy a gene it must be glued into a plasmid- plasmid must be removed from the host cell and cut open using a restriction endonuclease (gene splicing) Vector is placed inside the host bacterium and the bacterium is giving its ideal conditions to grow and proliferate. Done by placing a bacterium into a bioreactor.