T10 - Eukaryotes Flashcards
What kind of group are eukaryotes considered as?
Considered a monophyletic group
How did the first eukaryote arise?
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
what are some characteristics of eukaryotes?
- 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
What are photosynthetic eukaryotes?
Have both mitochondria and plastids
plastids; chloroplasts (photosynthesis), chromoplasts (fruit and flower pigmentation), amyloplasts (storage of starch = amylose)
What are chloroplasts?
Organelle that absorbs sunlight and uses it for the synthesis of organic compounds from CO2 ad H2O
Posess its own DNA
What are protists? What are some characteristics?
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
What are the disadvantages and advantages of sexual reproduction?
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
What types of life cycles correspond to the main groups within eukaryotes?
Diplontic = animals
Haplo-diplontic = plants and some algae
Haplontic = most fungi and some protists
What is bioluminescence? How is it used to some organisms advantage?
The production and emission of light
Can be used to scare predators away (mechanical stress = predator avoidance)
What are the main characteristics of fungi?
- reproduce sexually and/or asexually
- heterotrophs and decomposers
