Turning points 2: eukarya

Question 1

Which of the following statements best describes the difference between prokaryotes and eukaryotes?

a) Prokaryotic cells and eukaryotic cells differ only in their size
b) Eukaryotic cells have membrane-bound nucleus; prokaryotic cells do not.
c) Prokaryotes include only plants; eukaryotes include all other organisms.
d) Most eukaryotes are unicellular; most prokaryotes are multicellular.

Answer 1

b) Eukaryotic cells have a membrane-bound nucleus; prokaryotic cells do not

Question 2

what are protists?

Answer 2

• Includes all eukaryotic lineages except land plants, fungi, and animals.
• Paraphyletic group (no synapomorphies exclusive to protists)
• Range from bacteria sized single cell organisms to multicellular algae’s (ex. giant kelp)

Question 3

what is symbiosis

Answer 3

when individuals of two different species live in physical contact.

Question 4

What is Endosymbyosis?

Answer 4

when an organism of one species lives inside the cells of another species.

Question 5

Who is Lynn Marguilis?

Answer 5

Lynn Marguilis was regected by 15 scientific journals for her idea in 1967 that mitochondria was an endosymbiont (bacterium living inside eukaryotic cell). And in 1970 she published a book called “Origins of eukaryotic cells”.

Question 6

what are the Mitochondrial features consistant with endosymbiosis?

Answer 6

1. Mitochondria are similar in size to alpha proteobacteria
2. Replicate by fission, as do bacteria
3. Mt duplication occurs independently of host cell division
4. Mt have their own ribosomes, which are similar to bacterial ribosomes. (Affected by antibiotics that target bacterial ribosomes)
5. Have 2 membranes, consistent with engulfment
6. Have their own genomes, organized as circular molecules like bacterial chromosomes
7. Mt gene sequences are more closely related to alpha proteobacteria than to eukarya nuclear DNA.

Question 7

What is Phagocytosis?

Answer 7

form of ingestive feeding where the eukaryotic cell with a dynamic cytoskeleton can engulf another cell.

- Prey gets surrounded by a plasma membrane, which is pinched off

Question 8

what is Syntrophy?

Answer 8

(Cross-feeding) - where one species lives off products of another.

Question 9

What is a gametophyte?

Answer 9

Multicellular Haploid form
- Has specialized cells that produce gametes (single haploid cells) by mitosis
- Two gametes fuse to produce diploid zygote.
Gametophytes produce gametes by mitosis.

Question 10

What is a Sporophyte?

Answer 10

• Has specialized cells that produce spores (single haploid cells) by Meiosis
• Spores divide mitotically to form gametophytes.
  Multicellular diploid form.
  Sporophytes produce spores by meiosis.