Today is 25 January 2011 -- We learned about Mendelian Genetics

Today we learned about segregation, independent assortment and the concept by Gregor Mendel that two "elements" contributed to inheritance of characteristics. His work was long before scientists understood chromosomes and genes, and the discovery of DNA (deoxyribosenucleic acid). Be sure to understand the terms Mendel pioneered. What are: F1, F2, P1, recessive, dominant? How did statistical analysis of the results of Mendel's experiments (he used pea plants grown in the monastery garden as test subjects) lead him to formulate his laws of genetics? Why is this useful today?

Today is 15 December 2010 -- We are learning a little about cell growth and reproduction

Students had three questions to answer to see if they were paying attention. Here are the questions and a sampling of the answers:

1. How do metastases affect an individual with cancer?

"They can be convinced in other parts of the body."

"It spreads diseased cells to other parts of the body by way of blood or lymphatic vessels or membranous surfaces."

"The break-away cells can be carried in other parts of the body."

"It spreads faster."

"Allows the cancer cells to grow at a specific rate."

2. What does the "a" in asexual mean?

"One individual person."

"Single - erotic"

"Single - not having a partner."

"The 'a' in asexual refers to the asexual reproduction which needs only a single individual."

"No partner with you."

"It means you can create cancer."

"Means sex by yourself -- masturbation."

3. What is the difference between "benign" and "malignant?"

"I don't know."

"That they mean 2 different things and have different meanings."

"They are opposite."

"Benign is the cancer cells typically (grouped) together; malignant is a break-away cell."

"Benign is a growth that is not harmful and malignant is the opposite."

Most of the answers showed that the students had at least a passing acquaintance with the subject. Of course, a few students will be, I'm afraid, rather disappointed with the true meaning of "asexual." It means to reproduce the organism without the benefit of an exchange of genetic material with another individual. In this respect, the offspring is a clone of the parent.

Students were also assigned review questions 1, 2 and 3 on pages 137 and 142 of their text. The questions dealt with an understanding of the cell cycle (p. 137) and of mitosis (p. 142).

Bravo to those students who completed the homework and who really paid attention to details of the cell cycle!

Today is 11 January 2011 -- What do we need to know about Genetics?

Here are the California Standards for Genetics. We will not be studying each and every detail, but this gives you an idea of what topics there are within the subject area that students throughout California learn about.

2. Mutation and sexual reproduction lead to genetic variation in a population. As a basis for understanding this concept:

a. Students know meiosis is an early step in sexual reproduction in which the pairs of chromosomes separate and segregate randomly during cell division to produce gametes containing one chromosome of each type.

b. Students know only certain cells in a multicellular organism undergo meiosis.

c. Students know how random chromosome segregation explains the probabilitythat a particular allele will be in a gamete.

d. Students know new combinations of alleles may be generated in a zygote through the fusion of male and female gametes (fertilization).

e. Students know why approximately half of an individual’s DNA sequence comes from each parent.

f. Students know the role of chromosomes in determining an individual’s sex.

g. Students know how to predict possible combinations of alleles in a zygote from the genetic makeup of the parents.

3. A multicellular organism develops from a single zygote, and its phenotype depends on its genotype, which is established at fertilization. As a basis for understanding this concept:

a. Students know how to predict the probable outcome of phenotypes in a genetic cross from the genotypes of the parents and mode of inheritance (autosomal or X-linked, dominant or recessive).

b. Students know the genetic basis for Mendel’s laws of segregation and independent assortment.

c.* Students know how to predict the probable mode of inheritance from a pedigree diagram showing phenotypes.

d.* Students know how to use data on frequency of recombination at meiosis to estimate genetic distances between loci and to interpret genetic maps of chromosomes.

4. Genes are a set of instructions encoded in the DNA sequence of each organism that specify the sequence of amino acids in proteins characteristic of that organism. As a basis for understanding this concept:

a. Students know the general pathway by which ribosomes synthesize proteins, using tRNAs to translate genetic information in mRNA.

b. Students know how to apply the genetic coding rules to predict the sequence of amino acids from a sequence of codons in RNA.

c. Students know how mutations in the DNA sequence of a gene may or may not affect the expression of the gene or the sequence of amino acids in an encoded protein.

d. Students know specialization of cells in multicellular organisms is usually due to different patterns of gene expression rather than to differences of the genes themselves.

e. Students know proteins can differ from one another in the number and sequence of amino acids.

f.* Students know why proteins having different amino acid sequences typically have different shapes and chemical properties.

5. The genetic composition of cells can be altered by incorporation of exogenous DNA into the cells. As a basis for understanding this concept:

a. Students know the general structures and functions of DNA, RNA, and protein.

b. Students know how to apply base-pairing rules to explain precise copying of DNA during semiconservative replication and transcription of information from DNA into mRNA.

c. Students know how genetic engineering (biotechnology) is used to produce novel biomedical and agricultural products.

d.* Students know how basic DNA technology (restriction digestion by endonucleases, gel electrophoresis, ligation, and transformation) is used to construct recombinant DNA molecules.

e.* Students know how exogenous DNA can be inserted into bacterial cells to alter their genetic makeup and support expression of new protein products.

Today is 24 October 2008 - Here is practice for the biology Standard Assessment Test

These questions provide practice to assist the biology class to prepare for the Standard Assessment Test.  The questions are similar to those which are on the test, but they are not the same questions.   

1.  What are the following:

a.  Viruses

b. eukaryotic bacteria

c. prokaryotic bacteria

2.  What is an “organelle?”  What do the following organelles do?

a.  ribosome

b.  mitochondrian

c.  Golgi apparatus

d. nuclear membrane

3.  What is the difference between eukaryotes and prokaryotes?

a.  nucleus

b. protein coat

c. cell membrane

d. ribosome

e. ribosomal RNA

4.  What happens during the dark phase of photosynthesis?  What happens during the light phase?

5.  What do each of the following do?

a.  bases

b.  sugars

c.  fatty acids

d.  amino acids

6.  What is active transport?  Does it require or give up energy?

7.  What is facilitated diffusion?  Does it require or give up energy?

8.  What are the steps involved in protein synthesis? (I gave you an illustration of this.)

9.  Why do different cells have or make different proteins?

10.  What would produce an inactive protein that is smaller than it otherwise should be?

11.  Beside structural functions, what else do proteins do?

12.  What is a “codon?” Explain what a mRNA codon does or pairs with during translation.

13.  Dr. Frankenstein has spliced plant genes for chloroplasts into the chromosomes of termites.  His theory is that when the chloroplasts are exposed to sunshine, they will produce food for the termites so the insects will not need to bore into structural wood for food.  Where can you find reliable information on risks or benefits of his idea?

a.  T.V. news or radio talk shows.

b.  Internet news and blogs, especially “stop.com” (Stall Termites On Photosynthesis) 

c.  Science journals where other researchers analyze Dr. Frankenstein’s work.

d.  Igor, a spokesman for Dr. Frankenstein.

14.  What are proteins composed of?  Can different proteins (that is, different functions) contain the same number AND sequence of these components?

15.  In class, you chewed a cracker until it tasted sweet.  You learned  that the enzyme “amylase” in your saliva broke the starch in the cracker down to simple sugars.  What would taste sweet faster:  chewing a whole cracker all at once, or nibbling a little piece?  Why?

16.  What precisely do ribosomes do?  (Detailed explanation)

17.  If you have a skin condition, some doctors recommend soaking in salt water?  Why?  On the other hand, what would happen if you soak in distilled water?   What does this suggest to you about the balance of salts in or out of body cells?  What would happen if we soaked a stalk of celery in salt water?  In distilled water?

18.  We demonstrated how DNA is transcribed to messenger RNA which then travels to the ribosome.  At the ribosome, transfer RNA’s bearing amino acids bind to the mRNA bases such that a guanine on the tRNA binds to an cytosine on the mRNA, and an adenine on the tRNA binds to a uracil on the mRNA.  It takes a set of three bases on the mRNA, called codons, to bind to three opposite bases on the tRNA, called anticodons.  Find a genetic code chart in your book.  If the anticodon is Adenine-Adenine-Adenine (abbreviated AAA), what amino acid is specified by the codon?

19. Antibiotics lose effectiveness when bacteria mutate.  Surviving bacteria then grow to recolonize an infected site.  If the genetic material (genome) of the original bacteria is a little different from the genome of the now resistant organisms, what does that tell you about mutations?

20.  Sketch the process of protein synthesis starting with the double helix of DNA.

21.  Sickle-cell anemia is caused by a mutation that changes the DNA sequence from CAT to CTT.  Then, the mRNA codon sequence changes from GUA to GAA and the amino acid that is specified changes from Valine to what?  Use the genetic code chart in your book to find out.

22.  What is “genetic engineering?”  What are some of the success stories due to genetic engineering?

23.  What do the following organelles do?

a.  nucleolus

b.  ribosome

c.  lysosome

d.  mitochondrian

24.  How important is it to be accurate when you observe science experiments?

25.  When you study figures, understand them thoroughly before working on the problem that they serve to illustrate.

26. Viruses are a little like aliens in horror stories.  Once they infect you, they can add their genetic material to your own.  But they can lay dormant for years and, since their genetic material is mixed with yours, it can be transferred to subsequent generations.  What does this tell you about trying to “breed” infection out of a plant or animal?