1. Biology Domain 3
Genetics

2. Biology Standard 2:
Students will analyze how biological traits are passed on to successive generations.

3. A. Basic Stuff 1. DNA a. contains all genetic material
b. instructions for LIFE
c. found in nucleus of eukaryotic cells and nuclear region of prokaryotic cells

4. 2. Traits a. all characteristics of an organism
b. located on genes found on DNA
c. passed from parent to offspring

5. B. Nucleic Acids 1. DNA a. deoxyribonucleic acid
b. found in the nucleus
c. double helix
d. stores genetic information

6. Don’t forget… Base-pairing rules for DNA Adenine (A) – Thymine (T)
Cytosine (C) – Guanine (G)

7. Now think about this:
In a sample of yeast DNA, 31.5% of the bases are adenine (A). Predict the approximate percentages of C, G, and T. Explain.

8. b. made in the nucleus, moves to ribosomes to make proteins
2. RNA
a. ribonucleic acid
b. made in the nucleus, moves to ribosomes to make proteins
c. single stranded
d. transmits genetic information
e. 3 types (messenger, transfer, ribosomal)
mRNA, tRNA, rRNA

9. Don’t forget… Base-pairing rules for RNA Adenine (A) – Uracil (U)
Cytosine (C) – Guanine (G)

10. 3. How are nucleic acids made?
a. DNA Replication
1. occurs in nucleus
2. DNA uncoils and new DNA is added
3. occurs before cell reproduces so that both cells have a full set of instructions

11. b. RNA transcription
1. occurs in nucleus
2. single strands of RNA are made from information in DNA
3. RNA leaves nucleus to direct the making of proteins on the ribosomes (protein synthesis)

12. Now think about this…
If a DNA segment has the nucleotides AGCTAA, what would be the nucleotide sequence of the complementary RNA strand?

13. One more!
If an mRNA strand reads GUC UAG CAU UUC, what was the DNA template that was used to produce this mRNA strand?

14. c. Protein Synthesis
1. also called translation
2. information originally found in DNA is translated into proteins for body functions
3. occurs on ribosomes
4. Genetic Code is translation guide

15. Don’t forget…
When using the genetic code, the DNA, mRNA, and tRNA are read in triplets (3 bases at a time!
mRNA triplets are called codons, tRNA triplets are called anticodons
The GENETIC CODE on your handout and in MOST textbooks works using mRNA codons!

16. Now, think about this…
Use the genetic code to translate the following DNA strand into the correct amino acid sequence.
DNA: CAG TGC CTT TTG ACT
mRNA:
Amino acids:

17. Now, try this one…
Use the genetic code to translate the following DNA strand into the correct amino acid sequence.
DNA: ATG AGA AGT AGG TAG
mRNA:
Amino acids:

18. Last one…
Use the genetic code to translate the following DNA strand into the correct amino acid sequence.
DNA: TAC TTA ATC CCC GCC
mRNA:
Amino acids:

19. C. Cell Reproduction
1. Cells must reproduce for growth and development and to produce offspring
2. 2 Types of Cell Reproduction
a. Mitosis
b. Meiosis

20. 3. Mitosis
a. occurs for growth and development in multicellular organisms
b. simple ASEXUAL reproduction in unicellular organisms
c. cells are reproduced EXACTLY
d. DNA (chromosomes) are always copied completely before mitosis occurs so both new cells have an exact copy

21. 4. Meiosis
a. traits are passed to offspring on chromosomes that are inherited from parents
b. Mom donates half in an egg, Dad donates half in sperm
c. Egg and sperm are produced through meiosis and are NOT identical to original cells

22. Try this! Which occurs during meiosis, but not during mitosis?
A. the nuclear membrane disappears
B. two divisions of the cell
C. cytokinesis of the parent cell
D. production of 2 daughter cells

23. Try this!
The process in the diagram does NOT result in the formation of a
A. diploid cell
B. haploid cell
C. sex cell
D. gamete

24. Try this!
Chromosomes determine all inherited traits because they are made up of
A. DNA
B.ATP
C. Centromeres
D. Chloroplast

25. d. Genetic Variation
1. when eggs and sperm are made, DNA CROSSES OVER (genetic information is switched)
2. the cell splits twice, so only half of the original information is found in sperm and egg (REDUCTION DIVISION)
3. genetic information is crossed and halved RANDOMLY

26. e. Chromosomes
1. DIPLOID--most cells have 2 copies of all genetic information (one copy from mom and one from dad)
2. HAPLOID--Cells produced through meiosis only have one copy of genetic information
3. Sexual reproduction—haploid egg + haploid sperm = diploid zygote

27. Try this!
Genetic variation can arise in a number of different ways. The picture shows an example that occurs during meiosis. What example does the drawing show?
A. fertilization
B. segregation
C. crossing-over
D. independent assortment

28. Try this!
Which term describes the rearrangement of genes in offspring that differ from those of their parents?
A. recombination
B. mutation
C. mitosis
D. asexual reproduction

29. Warm-up
What are different versions of a gene for the same trait called?
A. phenotypes
B. alleles
C. hybrids
D. homozygous

30. D. Heredity
1. Traits are passed from parent to offspring through sexual (sometimes asexual) reproduction)
2. Gregor Mendel
a. father of Genetics
b. conducted research on peas
c. proposed several laws concerning heredity

31. 3. Mendel’s Laws a. Law of Segregation
1. gene pairs separate during meiosis
2. you only get half of mom’s DNA and half of dad’s DNA
b. Law of Independent Assortment
1. gene pair separation for one trait does not affect others
2. genes for height separate independently of genes for hair color

32. c. Law of Dominance
1. you have two copies of a gene for any given trait (alleles)
2. some copies are DOMINANT and some are RECESSIVE
3. DOMINANT masks RECESSIVE
4. Dominant Alleles—Capital Letter
5. Recessive Alleles—Lowercase Letter

33. Try this!
A human zygote, like most other human cells, contains 46 chromosomes. How many chromosomes does a human zygote receive from its mother?
A. 0
B. 23
C. 46
D. 92