GENETICS PowerPoint PPT Presentation

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2. Genetics—what is it? ? the study of how traits are passed from the parent to the offspring Trait ? a feature or characteristic something has What determines your traits? -- combination of genes Genes ? a small section of chromosome that determines a specific trait

3. Genetics DNA ? deoxyribonucleic acid Type of Macromolecule: Nucleic Acid Known as “Life’s Code” and as a “Double Helix” ? a molecule that makes up the genes and determine what trait something has RECAP: DNA makes up Genes that make up Chromosomes

4. Structure of DNA DNA looks like small strand of DNA a ladder

5. Structure of DNA Sides of the DNA are made up of: Sugar (Deoxyribose) Phosphate Rungs of the DNA are made up of NITROGEN BASES: 1. Adenine 2. Thymine 3. Guanine 4. Cytosine

6. Structure of DNA Nitrogen Bases always form PAIRS: Adenine is always with Thymine (AT) Cytosine is always with Guanine (CG) Nucleotide ? the combination of sugar, phosphate, and a nitrogen base The genetic code that our DNA forms is based on how the nitrogen bases form.

7. GENETIC CODE A change in just 1 pair of DNA bases can change a living things traits!! The genetic code sends a message as to what type of PROTEIN needs to be made, which tells what type of trait needs to be made Let’s take a look at the board and read the genetic code of the piece of DNA Mrs. Miley has drawn on the board


9. DNA REPLICATION ? this is how DNA and chromosomes are copied Happens 2 ways: 1. Mitosis 2. Meiosis

10. DNA REPLICATION Steps in DNA Replication: 1. DNA is ready to copy itself 2. The molecule begins to be “unzipped” up along its middle— this is done with the help of ENZYMES! 3. Each side has now been unzipped and has to reconnect to floating nitrogen bases Remember: A joins with T and G joins with C 4. When all the nitrogen bases have been joined you now have 2 new DNA molecules


12. What happens when something goes wrong during DNA REPLICATION? MUTATION ? this is any change that happens when the DNA is copying itself A does NOT join with T OR C does NOT join with G If a mutation occurs, then the genetic code will send the wrong message and produce the wrong PROTEIN Remember that 3 bases code for 1 amino acid so if it is mutated it will be off THE DOG BIT THE CAT THE DOG BIT THE CAR ****1 letter can change the whole meaning of the message!!!

13. MUTATIONS How do they occur? 1. copying errors when the DNA replicates 2. outside factors: radiation---examples: sun & X-rays Mutations can be good or bad: good:--helpful traits is produced Bad: --results in a protein that does not work correctly --causes cell to function incorrectly -- can cause genetic disorders

14. MUTATIONS ?enzymes go through and check to make sure nucleotide sequences are correct and will repair them if they are not, however they are not perfect! ? can cause genetic disorders to happen We will be investigating genetic disorders later on in this unit!

15. TYPES OF MUTATIONS POINT MUTATIONS— a change in just 1 base pair in the DNA FRAMESHIFT MUTATIONS— when 1 base pair is added or deleted from the DNA CHROMOSOMAL MUTATIONS— when something happens and the chromosome breaks and rejoins incorrectly

16. TYPES OF CHROMOSOMAL MUTATIONS DELETIONS— this is when a part of the chromosome is left out INSERTIONS— part of the chromatid breaks off and attaches to its sister chromatid INVERSIONS— part of the chromosome breaks off & is reinserted backwards TRANSLOCATIONS– when part of the chromosome breaks off & is added to a different chromosome

17. GENES ? small section on a chromosome that determines a specific trait GENES on a sex cell---single GENES on a body cell---pairs Each trait has either: 1 gene pair OR 2 genes

18. GENES 2 types of Genes can be passed from the parent to the offspring DOMINANT GENES ? genes that keep other genes from showing up (symbol: upper case letter: T) RECESSIVE GENES ?the genes that show up only when dominant genes are not there (symbol: lower case letter: t)

19. GENES ALLELES ?different forms of genes for each trait Example: Seed shape: round or wrinkled Flower color: purple or white Plant height: short or tall

20. GENE Combinations Dominant genes and Recessive Genes can combine to be either: HOMOZYGOUS ?both genes are the same -- 2 dominant genes (PURE DOMINANT) OR -- 2 recessive genes (PURE RECESSIVE) HETEROZYGOUS ? --has 1 dominant gene & 1 recessive gene The DOMINANT GENE always shows its trait!!!!

21. Gene Combinations Lets look at some examples on the board:

22. Gene Combinations You can predict what traits your offspring will have! However sometimes your prediction will be off Expected Results ?results that can be predicted using a punnett square Observed Results ?results or traits that we can actually SEE or OBSERVE on someone

23. Expected/Observed Results If 2 parents both have brown hair we would expect their offspring to have brown hair. However, that offspring might have blonde hair which would be the observed result.

24. REMEMBER…. PHENOTYPE ?regardless of its genes, the outward or physical trait that is seen (OBSERVED RESULT) GENOTYPE ?the combination of genes for a trait (EXPECTED RESULT)

25. PUNNETT SQUARE ?this is a visual way to see which genes combine when egg & sperm join Trait: Fur color Recessive gene: white (t) Dominant gene: black (T) The father dog is heterozygous (Tt) and has black fur while the mother dog is homozygous and is pure recessive (tt) and has white fur. What is the chance that 1 pup will have white fur?

26. GREGOR MENDEL ?linked with explaining laws of genetics Experimented on PEA PLANTS

27. INCOMPLETE DOMINANCE ?when neither gene is dominant over the other one so a new trait is produced A new trait results from the blending of these 2 traits Example: red snapdragons combine with white snapdragons = pink snapdragons Let’s take a look at the board & do a punnett square

28. INCOMPLETE DOMINANCE SICKLE-CELL ANEMIA ?genetic disorder in which all the red blood cells are shaped like sickles and do not carry enough oxygen Healthy red blood cells = RR Sickle cells = R’R’ Let’s do a punnett square on the board

29. OTHER TYPES OF GENE COMBINATIONS: CODOMINANT TRAITS? when both genes are dominant so both traits show up equally POLYGENIC TRAITS? when there is one trait controlled by many genes Example: hair color, weight


31. TRAITS FOUND ON THE X-Chromosome 1. Blood clotting 2. color blindness 3. tooth color 4. skin dryness These are located on the x-chromosome so males have a higher chance of having these traits

32. CHROMOSOMES ? cell structured located in the nucleus that carries the genes and genetic material Chromosome #’s: Each human sperm cell has 23 chromosomes Each human egg cell has 23 chromosomes Each human body cell has 23 pairs or 46 chromosomes Different organisms have different #s of chromosomes

33. CHROMOSOMES ?whether you are a boy or a girl depends on your chromosomes You have 23 pairs of chromosomes 22 are autosomes—do not determine the sex of a person 1 pair are sex chromosomes—determine the sex of a person X-chromosome = sex chromosome for the FEMALE Y-chromosome = sex chromosome for the MALE XX = female XY = male

34. CHROMOSOMES Is this person a male or a female?

35. CHROMOSOMES Who determine what sex the child will be? Female = XX Male = XY

36. RNA ?ribonucleic acid ?macromolecule: Nucleic Acid Differs from DNA in 3 ways: 1. RNA is a SINGLE strand of nucleotides 2. the sugar in RNA is RIBOSE 3. RNA has the Nitrogen Base---Uracil instead of Thymine Hmmm…..which nitrogen base will U combine with?

37. RNA What is RNA’s job? RNA takes orders from the DNA and synthesis (makes) proteins

38. 3 types of RNA 1. messenger RNA (mRNA) ?brings info from the nucleus to the cytoplasm 2. ribosomal RNA (rRNA) ?use the info from the mRNA to assemble the Amino Acids in the correct order 3. transfer RNA (tRNA) ?transports the Amino Acids that the rRna made to the RIBOSOMES and are assembled into PROTEINS

39. RNA VOCABULARY TRANSCRIPTION ?enzymes make a RNA copy of the DNA strand so that the RNA can then take the DNA information elsewhere in the cell TRANSLATION ? this is the process of the mRNA passing the information to the rRNA and then passing that information to the tRNA for a protein to be made TAKES PLACE in the RIBOSOMES

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