1. Unit 4 Part 1

3.  DNA cannot leave the nucleus.  Through transcription an mRNA copy of DNA is made.  RNA Polymerase unwinds and unzips the DNA.  RNA Polymerase adds RNA nucleotides one at a time until it reaches a stop point on the DNA.  Once it reaches the stop point the mRNA sequence is released into the cytoplasm.

4.  After the mRNA sequence is released into the cytoplasm it attaches to a Ribosome.  The ribosome travels down the mRNA strand looking for a start codon (AUG).  After it finds the start codon a tRNA molecule attaches to the mRNA codons by an Anti-codon and drops off a specified amino acid. A.A. Anti-codon

5.  What happens if a mistake is made during one of these processes?  A mutation may result.  What is a mutation?  Changes in the nucleotide sequence of DNA. ▪ May occur in somatic. cells (Acquired - aren’t passed to offspring). ▪ May occur in gametes. (eggs & sperm) and be passed to offspring (inherited.)

6.  Random mistakes in the reproductive process or the transcription /translation process.  Chemicals:  Radiation:

7. 1.Chromosome Mutations  Affects a large of DNA  5 types ▪ Deletion ▪ Inversion ▪ Insertion. ▪ Translocation ▪ Non-disjunction

8.  Deletion  Due to subtraction.  A piece of a chromosome is lost.  Inversion  Chromosome segment breaks off & flips.  Segment reattaches.

9.  Duplication  When an entire gene segment is copied.  Translocation  When 2 non homologous chromosomes cross over.

10.  Nondisjunction  Failure of chromosomes to separate during meiosis.  Causes gamete to have too many or too few chromosomes.  Is the cause of many genetic disorders.  EX. Trisomy 21

11. 2. Gene Mutations  Include: ▪ Point Mutations ▪ Frameshift  Change in the N base sequence of a gene.  May only involve a single nucleotide.  May be due to copying errors, chemicals, viruses, etc.

12.  Change in the nucleotide sequence of a gene.  May only involve a single nucleotide.  May be due to copying errors, chemicals, viruses, etc.

13.  Point Mutation  Change of a single nucleotide.  Includes the deletion, insertion, or substitution of ONE nucleotide in a gene. ▪ EX. Sickle Cell Anemia

14.  Frameshift Mutation  Inserting or deleting one or more nucleotides.  Changes the “ word(codon)” like changing a sentence.  Proteins built _change_.

15. Unit 4 Part 1

16.  A picture of the collection of chromosomes found in an individual’s cells.  Tells you the chromosome number of an organism.  46 in humans.  Tells you the sex of an organism:  XX = Female XY = Male  Can indicate whether or not a chromosomal abnormality is present.

17. MALEFEMALE

18. MONOSOMY  the condition in which a diploid cell is missing a chromosome. TRISOMY  the condition in which a diploid cell has an extra chromosome.

19.  Down Syndrome  Extra 21 st Chromosome.  Symptoms: ▪ Distinctive shaped eyes ▪ Cognitive heart abnormalities ▪ Simian folds ▪ Below average cognitive ability ▪ Protruding tongue ▪ Short limbs

20.  Turner’s Symdrome  1 X chromosome and no match.  Symptoms ▪ Short stature ▪ Webbed neck ▪ Broad chest ▪ Non-functioning ovaries ▪ sterility

21.  Klienfelter’s Syndrome  2 X chromosomes and 1 Y  Most common chromosomal abnormality. ▪ Symptoms ▪ Underdeveloped male sex characteristics. ▪ Reduced fertility. ▪ Slightly feminime characteristics. ▪ Potential language impariment.