T10 - Eukaryotes

Question 1

What kind of group are eukaryotes considered as?

Answer 1

Considered a monophyletic group

Question 2

How did the first eukaryote arise?

Answer 2

Endosymbiosis; integration of an aerobic bacteria which evolves into mitochondria and allows for aerobic cellular respiration in the now eukaryote

Entrapping of an aerobic bacteria

Question 3

what are some characteristics of eukaryotes?

Answer 3

• plasma membrane = constitues a selective barrier with the environment
• cytoplasm = total content of the cell bounded by the plasma, excluding the nucleus
• cytosol = internal fluid containing organic molecules, proteins, metabold waste
• organelles = membrane enclosed structures with specialized functions
• inclusions = particles of insoluble substances (water is the solvent)
• nucleus = contains genetic material in form of chromosomes - made of chromatin (DNA and proteins - histones) and surrounded by nuclear envelope
• ER = membranous network
  rough ER (ribosome studded) = synthesis of proteins
  smooth ER (ribosome free) = synthesis of lipids, carbohydrate, Ca+ storage…
• golgi apparatus = protein and phospholipid mods (post translational)
• mitochondrion = double membrane bound organelle for cellular respiration, possesses its own DNA
• cytoskeleton = network of microtubules, microfilaments and intermediate filaments to give the shape of the cell and act as highways within
• peroxisome = oxidative organelle, transferring hydrogen atoms to oxygen, producing and degrading H2O2
• lysosome = digestive organelle, macrophages will eat dying cells and clean up debris

Question 4

What are photosynthetic eukaryotes?

Answer 4

Have both mitochondria and plastids

plastids; chloroplasts (photosynthesis), chromoplasts (fruit and flower pigmentation), amyloplasts (storage of starch = amylose)

Question 5

What are chloroplasts?

Answer 5

Organelle that absorbs sunlight and uses it for the synthesis of organic compounds from CO2 ad H2O

Posess its own DNA

Question 6

What are protists? What are some characteristics?

Answer 6

Any eukaryote that is not a plant, animal or fungus

• Most are unicellular
• large diversity in nutrition (photoautotrophs, heterotrophs, mixotrophs - combination of photo and heterotrophs)
• large diversity in reproduction (asexual and sexual)
• life cycles can be; haplontic, diplontic, haplo-diplontic

Question 7

What are the disadvantages and advantages of sexual reproduction?

Answer 7

D;

• takes time and energy to look for a sexual partner, time not spent feeding
• an indiv ‘dilutes’ its own genes every eneration
• reprod output it decreased by half for a given sex (one does not contribute typically males)
• two fold cost of sex; decrease in reprod output + dilution of genes

A;

• new genetic combinations can be beneficial for changing environments
• eliminatio of deleterious alleles from the population
• can speed up adaptation

Question 8

What types of life cycles correspond to the main groups within eukaryotes?

Answer 8

Diplontic = animals

Haplo-diplontic = plants and some algae

Haplontic = most fungi and some protists

Question 9

What is bioluminescence? How is it used to some organisms advantage?

Answer 9

The production and emission of light

Can be used to scare predators away (mechanical stress = predator avoidance)

Question 10

What are the main characteristics of fungi?

Answer 10

• reproduce sexually and/or asexually
• heterotrophs and decomposers