Wednesday, March 25, 2015

I mentioned this animal in class when we were discussing photosynthesis.

This beautiful green leafy organism is actually a sea slug. The sea slug Elysia chlorotica consumes chloroplasts when it eats the algae Vaucheria litorea. The slug feeds on the algae, but the chloroplasts are retained in the cells of the gut. The gut in this sea slug is highly branched and the chloroplasts give it the green color. The chloroplasts in the tissue of the animal's gut continue to function in the animals without an algal cell being present. The slug lives about 10 months and can survive off the food made by the chloroplasts.

The green color also provides great camouflage. While the animal has to eat an algae to get the chloroplasts, it is intriguing that the chloroplasts can continue to function without any algal cells present as genes in the nucleus of the algae are needed for photosynthesis to occur. So where are the genes to support photosynthesis? In the nucleus of the sea slug cells! The slug gets the genes from the algae, it does not have them until the animal feeds on the algae.

Interested in looking into this gene transfer further? Click here to read a paper by Mary E. Rumpho et al. on horizontal gene transfer between the algae and the slug.

Photosynthesis from Space

When the chloroplasts in the leaves of plants absorb sunlight, some of the light is released from the leaves in a phenomenon called fluorescence. The light that is released is too dim for our eyes to see it, but it can be seen from satellites in space. Take a look. Click here to watch a short video of this fluorescence

Wednesday, March 4, 2015

Bio 120 review for Exam 2

DNA and Genetic Engineering Review Questions

1. Describe the structure of the DNA molecule

2. If the sequence of bases on one stand of the molecule is AAC TGC CCG, what is the sequence on the complementary strand?

3. During DNA replication, what enzyme breaks the hydrogen bonds between the base pairs, and what enzyme matches up nucleotides to the existing ones on the parent strand of DNA?

4. Why is this type of replication called Semi Conservative?

5. How is RNA different from DNA?

6. The production of messenger RNA from DNA is called ________, and this happens in the __________ of the cell.

7. mRNA gets a cap and a tail prior to being read by the ribosome. What is the function of the cap and tail?

8. If the DNA strand being copied had this sequence: ACT GGC ATA CTA what would the sequence of the mRNA be?

9. The function of transfer RNA is ?

10. What is the name of the enzyme that produces RNA from DNA?

11. If the sequence of DNA is the same in your body cells, why are all cells not the same?

12. The DNA in you, an earthworm, and a fungus is the same. So why are you a human and not an earthworm?

13. What is an anti-codon and where is it found?

14. The protein synthesis process that occurs at the ribosome is called _____________

15. What is a stop codon, and what happens when one is read in the ribosome?

Genetic Engineering  

1. What are restriction enzymes?

2. What kind of cells have restriction enzymes, and what is the purpose of these enzymes in the cell?

3. What is a plasmid?

4. How are plasmids used in genetic engineering?

5. Why does human DNA work in a bacterial cell?

6. What is gene therapy?

7. How are small fragments of DNA separated during the DNA fingerprinting process?

8. What benefits are there to inserting a human gene into a bacterium? What possible problems could arise from genetically engineered organisms being released into the wild?

Mitosis and Meiosis Review

1. If a cell has 8 chromosomes and does mitosis, how many cells will be made, and how many chromosomes will each cell have?

2. If a cell has 8 chromosomes and does meiosis to make sperm cells, how many cells will be made, and how many chromosomes will each cell have?

3. Mitosis creates cells which are ________, while meiosis makes cells which are _____.

4. What are homologous chromosomes?

5. What are sister chromatids?

6. What is crossing over, and during which process, (mitosis or meiosis) does it occur?

7. Why is crossing over important?

8. During __________ of mitosis sister chromatids separate.

9. During _________ of meiosis homologous pairs of chromosomes separate, but during ____________ of meiosis sister chromatids separate.

10. In meiosis, typically four sperm cells are made, but meiosis only makes one large egg cell. Why?

Plant Diversity

1. Which of the following is found in gymnosperms, and which is found in angiosperms?

A. seeds
B. pollen
C. Vessel cells in xylem
D. tracheid cells in xylem

2. What is the function of the anther in the flower?

3. Which of the following is where one would find ovules?

A. in an anther
B. in the ovary
C. in the stigma
D. in the style

4. Ovules are

A. eggs
B. spores that will become pollen
C. spores that will become eggs
D. immature seeds
E. pollen grains

5. In double fertilization the first sperm fertilizes the egg and the second

A. dies
B. is only used if the first sperm cell dies
C. fertilizes another egg
D. fertilizes a haploid endosperm mother cell to make diploid endosperm
E. fertilizes a diploid ( n+n) endosperm mother cell to make triploid endosperm

6. What is the function of fruit?

7. Microspores become
A. the embryo sac
B. the mature male gametophyte
C. pollen grains
D. eggs
E. only B and C above

8. What is the oldest plant on Earth, and what is the most massive

9. How are confiers adapted to life in cold dry climates?

10. What is missing in moss that is present in ferns?
A. swimming sperm
B. seeds
C. pollen
D. vascular tissue
E. ovules

11. Why are flowering plants so much more diverse than the gymnosperms?

12. What do ferns and mosses share in common?
A. seeds
B. swimming sperm
C. pollen
D. vascular tissue
E. dominant sporophyte generation

13. During a plant's life cycle the _______ generation is diploid and makes spores
A. sporophyte
B. gametophyte
C. sori
D. sporangia
E. photosynthetic

1. A lichen is made of a ____ and a ____. What is the ecological role of lichens?
2. What role do fungi play typically in their habitat?
3. How are fungi different from plants?
4. How do fungi feed?
5. How do fungi spread out in their habitat?
6. The body of a fungus is a thread like structure called a ____
6. A mass of the answer in question 6 is call a ____