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Genetics

Genetics . http://www.youtube.com/watch?v=CBezq1fFUEA&list=PL3EED4C1D684D3ADF. 4.1.1. State that eukaryote chromosomes are made of DNA and proteins. 4.1.2. Define gene , allele and genome . Gene- heritable factor that codes for a certain trait Ex: eye color

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Genetics

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  1. Genetics http://www.youtube.com/watch?v=CBezq1fFUEA&list=PL3EED4C1D684D3ADF

  2. 4.1.1 State that eukaryote chromosomes are made of DNA and proteins.

  3. 4.1.2 Define gene, allele and genome.

  4. Gene- heritable factor that codes for a certain trait • Ex: eye color • Allele- what will be expressed in that gene • Ex: blue eyes • Genome- Collection of all of an organism’s genes • usually encoded in DNA • HGP

  5. 4.1.3 Define gene mutation.

  6. Sequence change • Different amino acid possible • Can be beneficial • Mutagens

  7. 4.1.4 Explain the consequence of a base substitution mutation in relation to the processes of transcription and translation, using the example of sickle-cell anemia.

  8. 1/655 African Americans • Single base change • Change beta chain shape (needles)

  9. 4.2.1 State that meiosis is a reduction division of a diploid nucleus to form haploid nuclei.

  10. 4.2.2 Define homologous chromosomes.

  11. Same • Length • Loci for genes • Shape

  12. 4.2.3 Outline the process of meiosis, including pairing of homologous chromosomes and crossing over, followed by two divisions, which results in four haploid cells.

  13. http://www.youtube.com/watch?v=qCLmR9-YY7o&list=EC3EED4C1D684D3ADFhttp://www.youtube.com/watch?v=qCLmR9-YY7o&list=EC3EED4C1D684D3ADF

  14. Interphase • Chromosomes not condensed • DNA replicates- S1

  15. Prophase I • Nuclear membrane breakdown • DNA condensing • Spindle fibers • Centrioles move • Move towards equatorial plate • Longest phase of meiosis

  16. Metaphase I • Line up in center • Chromosomes most condensed • Crossing over (Metaphase and Prophase)- chiasma • Independent assortment

  17. Anaphase I • Homologous pair movement • “Arrow shape” of pairs

  18. Telophase I • Sets at opposite sides • Nuclear membrane may reform (species) • Cleavage furrow • End meiosis I

  19. Prophase II • Nuclear membrane breaks down • Spindle fibers reform

  20. Metaphase II • Line up center • Independent assortment

  21. Anaphase II • Spindle fibers contract • One chromatid per pole

  22. Telophase II • Nuclear membranes form • Haploid • Crossing over variation

  23. 4.2.4 Explain that non-disjunction can lead to changes in chromosome number, illustrated by reference to Down syndrome (trisomy 21).

  24. Can happen in Meiosis I or II • Result in too few or too many of one chromosome • Monosomy-more deadly, trisomy

  25. 4.2.5 State that, in karyotyping, chromosomes are arranged in pairs according to their size and structure.

  26. Pictures during metaphase • 23 pairs

  27. 4.2.6 State that karyotyping is performed using cells collected by chorionic villus sampling or amniocentesis, for pre-natal diagnosis of chromosome abnormalities.

  28. Obtain fetal cells to do a karyotype to find out if baby has disorder like Downs • Amniocentesis- removal of amniotic fluid containing fetal cells • Centrifuge separates chromosomes into size • Chorionic villus sampling- samples chorion • Must be after 8 weeks of pregnancy • Uses catheter

  29. 4.2.7 Analyse a human karyotype to determine gender and whether non-disjunction has occurred.

  30. 4.3.1 Define genotype, phenotype, dominant allele, recessive allele, codominant alleles, locus, homozygous, heterozygous, carrier and test cross.

  31. 4.3.2 Determine the genotypes and phenotypes of the offspring of a monohybrid cross using a Punnett grid.

  32. 2:2 ratio • Heterozygous crosses 3:1 • Each fertilization independent of others • Larger the population, the closer to expected ratio

  33. 4.3.3 State that some genes have more than two alleles (multiple alleles).

  34. Creates more phenotypes and genotypes • Example: Rabbit coat colour(C) has four alleles which have the dominance hierarchy: C > cch > ch> c • This produces 5 phenotypes, Dark(C_) , Chinchilla( cchcch), light grey (cchch,cchc), Point restricted (chch, chc) and albino (cc)

  35. 4.3.4 Describe ABO blood groups as an example of codominance and multiple alleles.

  36. I is immunoglobulin • The Allele hierarchy is IA = IB > I • When A and B present, both expressed and both mask O

  37. 4.3.5 Explain how the sex chromosomes control gender by referring to the inheritance of X and Y chromosomes in humans.

  38. 23rd pair • X much longer than Y • X from mom Y from dad in boys • Theoretically 50/50 chance for gender, but some have predisposition • SRY gene (supposed to be found on tip of Y) determines gender

  39. 4.3.6 State that some genes are present on the X chromosome and absent from the shorter Y chromosome in humans.

  40. 4.3.7 Define sex linkage.

  41. Genes on non-homologous region of X • Females spare tire other X, males don’t have this • More common in males • Boys inherit these from mom

  42. 4.3.8 Describe the inheritance of colour blindness and hemophilia as examples of sex linkage.

  43. Genes on non-homologous part of X • Males always get affected gene from mother • Males cannot pass on affected gene to sons, but can to daughters

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