How does DNA evolve Mutations can change the

How does DNA evolve?

Mutations can change the meaning of genes: the function of proteins – A mutation is a change in the nucleotide sequence of DNA – Base substitutions: replacement of one nucleotide with another – Effect depends on whethere is an amino acid change that alters the function of the protein – Deletions or insertions – Alter the reading frame of the m. RNA, so that nucleotides are grouped into different codons – Lead to significant changes in amino acid sequence downstream of mutation – Cause a nonfunctional polypeptide to be produced Copyright © 2009 Pearson Education, Inc.

https: //www. youtube. com/watch? v=9 b. Wjuw. Ti. YXI • http: //www. dnalc. org/resources/3 d/18 -dnadamage. html

Mutations can change the meaning of genes: The function of proteins – Mutations can be – Spontaneous: due to errors in DNA replication or recombination – Induced by mutagens – High-energy radiation – Chemicals (Usually detrimental) Copyright © 2009 Pearson Education, Inc.

Acquired mutations are changes in DNA that develop throughout a person's lifetime.

Hereditary mutations are carried in the DNA of the reproductive cells. When reproductive cells containing mutations combine to produce offspring, the mutation will be in all of the offspring's body cells

Accidents during meiosis can alter chromosome number – Nondisjunction is the failure of chromosomes or chromatids to separate during meiosis – During Meiosis I – Both members of a homologous pair go to one pole – During Meiosis II – Both sister chromatids go to one pole – Fertilization after nondisjunction yields zygotes with altered numbers of chromosomes Copyright © 2009 Pearson Education, Inc.

Nondisjunction in meiosis I

Nondisjunction in meiosis I Normal meiosis II

Nondisjunction in meiosis I Normal meiosis II Gametes n+1 n– 1 Number of chromosomes n– 1

Normal meiosis I

Normal meiosis I Nondisjunction in meiosis II

Normal meiosis I Nondisjunction in meiosis II Gametes n+1 n– 1 n Number of chromosomes n

Infants with Down syndrome (per 1, 000 births) 90 80 70 60 50 40 30 20 10 0 20 25 40 30 35 Age of mother 45 50

Abnormal numbers of sex chromosomes do not usually affect survival – Sex chromosome abnormalities tend to be less severe as a result of – Small size of the Y chromosome – X-chromosome inactivation – In each cell of a human female, one of the two X chromosomes becomes tightly coiled and inactive – This is a random process that inactivates either the maternal or paternal chromosome – Inactivation promotes a balance between the number of X chromosomes and autosomes Copyright © 2009 Pearson Education, Inc.

Klinefelters

Turner’s Syndrome

Genes, Inheritance and Biotechnology

Fraternal Twins

Inheritance Mendelian inheritance (or Mendelian genetics or Mendelism) is a scientific description of how hereditary characteristics are passed from parent organisms to their offspring; it underlies much of genetics.

Genetic Vocabulary • A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism • The genotype is the genetic makeup of a cell, an organism, or an individual • Allele Any alternative or same form of gene that can occupy a particular chromosomal locus. In humans and other diploid organisms there are two alleles, one on each chromosome of a homologous pair. • A phenotype (from Greek phainein to 'show' + typos 'type') is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior (such as a bird's nest). Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and the interactions between the two.

Karyotype Genotype Phenotype

Allele

Homologous Pairs

Punnett Square and Inheritance activities

Genomics is the scientific study of whole genomes – Genomics is the study of an organism’s complete set of genes and their interactions – Initial studies focused on prokaryotic genomes – Many eukaryotic genomes have since been investigated – Evolutionary relationships can be elucidated – Genomic studies showed a 96% similarity in DNA sequences between chimpanzees and humans – Functions of human disease-causing genes have been determined by comparisons to similar genes in yeast Copyright © 2009 Pearson Education, Inc.

Stem Cell Research • https: //www. youtube. com/watch? v=q. S 9 ZH 1 y GYfo

– Goals of the Human Genome Project (HGP) – To determine the nucleotide sequence all DNA in the human genome – To identify the location and sequence of every human gene Copyright © 2009 Pearson Education, Inc.

Genetic engineering involves manipulating genes for practical purposes – Gene cloning leads to the production of multiple identical copies of a genecarrying piece of DNA – Recombinant DNA is formed by joining DNA sequences from two different sources Copyright © 2009 Pearson Education, Inc.

GENE CLONING Copyright © 2009 Pearson Education, Inc.

Products of Gene Cloning – Therapeutic hormones – Insulin to treat diabetes – Human growth hormone to treat dwarfism – Diagnosis and treatment of disease – Testing for inherited diseases – Detecting infectious agents such as HIV Copyright © 2009 Pearson Education, Inc.

Genetic Engineering

History of Genetic Manipulations • In the 1970 s, scientists made a radical discovery. They could remove a gene from one species and force it into the DNA of another. No longer was sexual reproduction needed to create new types of offspring. And by transferring genes across the species barrier, the possible combinations became virtually infinite. • Scientists put spider genes into goats, in the hopes of milking the goat to get spider web proteins to make bullet proof vests. They’ve put genes into corn so the crop makes a spermicide. They’ve used jellyfish genes to make fish and puppies glow in the dark, created pigs with cow hides, and salmon that grow up to five times faster.

http: //www. youtube. com/watch? v=usn 7_CCN 9 H 4&f eature=related

Genetic Manipulation Helpful or Hurtful? • The Official Policy of the FDA is the GM foods poses no threat to human health • The American Academy of Environmental Medicine states that GM foods pose a serious health threat

Mansanto is biggest producer • States that increase food production by using GM seeds (developed them by taking genes from bacteria resistant to roundup and putting them into food crops) • Main crops: Soy, corn, cotton, canola, sugar beets and alfalfa

Round up resistance means more roundup

Different Proteins might be resulting in more compromised immune systems and more allergies

Safety studies on Potatoes • Pusztai’s team was working with a potato, outfitted with a gene from the snowdrop plant, that produced ‘GNA lectin’, a protein that kills insects. • When rats were fed these potatoes, certain organs shrank (brains) while intestinal walls thickened (precancerous)

• This is a lab rat that was genetically engineered to grow a human ear on its back. Is science going to far or is this a good thing? Especially for people awaiting organ transplants? What do you think?

Some bacteria digest toxic waste and produce electricity while doing it. Would this be good to harness?

Natural “Errors” may give species advantage

Darwin… 1831 -1836 22 years old!

Natural Selection: The process by which organisms with variations most suited to their local environment survive and have more offspring

Chromosome with allele conferring resistance to pesticide Additional applications will be less effective, and the frequency of resistant insects in the population will grow Pesticide application Survivors

Resistant Bacteria

MRSA

Humerus Radius Ulna Carpals Metacarpals Phalanges Human Cat Whale Bat

13. 5 A mass of other evidence reinforces the evolutionary view of life – Some homologous structures are vestigial organsstructures on/within an organism that does not seem to serve a function, but is suggestive of an evolutionary path back to an organism that did use that structure Copyright © 2009 Pearson Education, Inc.