1. 2 nd Quarter STAR Review

2. Chromosome Structure Chromosomes are rod-shaped structures made of DNA and protein.

3. Homologous Homologous chromosomes are similar in  SIZE  SHAPE  GENETIC CONTENT

4. Haploid: a single set a chromosomes. (23 total or n) Haploid: a single set a chromosomes. (23 total or n) Diploid: Two sets of chromosomes.(46 total or 2n) Diploid: Two sets of chromosomes.(46 total or 2n)

5. Gametes In humans it’s the:  SPERM (males)  EGG (females) They are HAPLOID!  Meaning they have HALF = 23 chromosomes

6. Zygote The fusion of a sperm & an egg cell results in zygote that contains 46(2n) chromosomes.

7. Fertilization Sperm + ovum ---  Zygote (n=23) (n=23) (2n=46) The formation of a zygote of a normal human male 22 X + 22 Y ----  44 XY The formation of a zygote a normal human female 22 X + 22 X----  44 XX

8. Formation of a zygote. The sex of the baby is determined by the DNA in the sperm.

9.  Which represents formation of male zygote?  Which represents formation of female zygote?

10. Which correctly models fertilization? B & D

11. Meiosis The process which results in four monoploid (haploid) gametes. The process which results in four monoploid (haploid) gametes. In Males, the meiosis takes place in the testis. In Males, the meiosis takes place in the testis. In females, the meiosis takes place in the ovaries. In females, the meiosis takes place in the ovaries. Creates gametes (sperm, egg). Creates gametes (sperm, egg).

13. Meiosis 2n n n nn n n

14. Crossing-over Parts of homologous chromosomes cross ‘arms’ and exchange pieces. Parts of homologous chromosomes cross ‘arms’ and exchange pieces. Takes place during Prophase I. Takes place during Prophase I. Source of genetic recombination. Source of genetic recombination.

15. Law of segregation It states that chromosomes are distributed to gametes in a random fashion. When gametes are formed, the pairs of hereditary factors (genes) become separated, so that each sex cell (egg/sperm) receives only one kind of gene.

16. Law of independent assortment It states that the alleles of different genes separate independently of one another during gamete formation. Genes get shuffled – these many combinations are one of the advantages of sexual reproduction

17. Law of Independent Assortment

19. Genetics GENETICS – branch of biology that deals with heredity and variation of organisms. Heredity The passing of traits from parents to offspring is called heredity

20. Dominant and Recessive Dominant: when a trait is expressed and one can see it. Recessive: when a trait is not expressed unless it is the only one available. Yy Yy Dominant Recessive Dominant yy yy There is only recessive

21. Homozygous: a pair of identical alleles  DD or dd Heterozygous: mixture of a dominant and recessive Dd PPpp Pp

22. Xx x x XxXxxx XxXx Cross: Heterozygous purple (Xx) Homozygous white (xx)

23. DNA DNA is often called the blueprint of life.

24. Composed of: phosphate backbone sugar (deoxyribose) Nitrogen Base Nucleotides P Sugar Nitrogenous Base

25. Bases Divided into two groups: Purines  Adenine (A)  Guanine (G) Pyrimidines  Thymine (T)  Cytosine (C) “Chargoff’s rule” A = T & C = G

26. Base-Pairing Rules AAGGTTCCTTAAGGCC

27. Base-Pairing Rules AAGGTTCCTTAAGGCC TTCCAAGGAATTCCGG

28. DNA Replication The process of making a copy of DNA. Takes place just before Mitosis and cell division.

29. DNA Replication

30. Replication A A T A C A G C G T A G T C G T A G C C G T T A T G T C G C A T C A G C A T C G G C Helicase A A T A C A G C G T A G T C G T A G C C G T T A T G T C G C A T C A G C A T C G G C Polymerase

31. How Proteins Are Made

32. Flow of Genetic Information DNA  RNA  Protein Nucleus: DNA acts as a template for the making of mRNA (TRANSCRIPTION) Ribosome: mRNA is read to code for specific amino acids that make up a protein. (TRANSLATION)

33. RNA DNA Single Strand Double Strand Ribose Deoxyribose Uracil Thymine ShortLong

34. Types of RNA  Cells have three major types of RNA: messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA)

35. RNA Structure and Function mRNA carries the genetic “message” from the nucleus to the cytosol. rRNA is the major component of ribosomes. tRNA carries specific amino acids, helping to form polypeptides.

36. Transcription The process of copying (from DNA) the instructions for making a protein

38. Transcription A T G C G C T C G G A C G T C G G A U AC GC G AG CCU G C A G C CU RNA Polymerase

39. mRNA Each 3-nucleotide group is called a ‘codon’ (AGG, etc). Each codon represents a specific amino acid to make during Translation.

41. Codon AGG GUC UAG ACG

42. Translation mRNA gets translated by a ribosome and allows tRNA to attach with a specific amino acid. anticodon Amino acid

43. Translation Steps 1. mRNA enters a ribosome.  The ribosome will not start translation until it reads the start codon (AUG) Ribosome Start codon mRNA

44. Translation Steps 2. tRNA arrives carrying specific amino acids linked to an anticodon. tRNA Start Codon Next Codon anticodon Amino acid mRNA Ribosome

45. Translation Steps 3. Anticodon, with correct amino acid, attaches to its specific codon, drops off amino acid, and detaches. Polypeptide Chain

46. Translation Steps 4. Steps 2 & 3 are repeated until entire protein chain is built and protein is released into cytoplasm.

47. Translation

48. Genetic Code The nearly universal genetic code identifies the specific amino acids coded for by each three-nucleotide mRNA codon.

49. TAC GAT TAG DNA TAC GAT TAG DNA AUG CUA AUC mRNA Start, Leucine, Isoleucine Codon

50. The Human Genome The entire gene sequence of the human genome, the complete genetic content, is now known. To learn where and when human cells use each of the proteins coded for in the approximately 30,000 genes in the human genome will take much more analysis.