Macromolecules and cells Flashcards
What is the evidence that mitochondria and chloroplasts originate from prokaryotes?
- Mitochondria and chloroplasts have their own cell membrane that is biologically similar to bacteria
- Both mitochondria and chloroplasts have their own DNA genome
- Both organelles are able to divide inside the eukaryotic cytoplasm
Describe prokaryotes
- Evolutionarily arose early (~3.5 billion years ago)
- Small ->2 x 1 micrometres
- Little internal organisation (lack membrane-bound organelles)
- Some have cell walls, but not made of cellulose (like plants)
- Obtain nutrients in a variety of ways, often through absorption
- Rapid growth via asexual reproduction
Genetic material (1 circular chromosome of DNA) but no nuclear membrane surrounding this - No true sexual reproduction but genetic exchange
What is eubacteria? What are some examples of the shapes of eubacteria?
Eubacteria is gram positive bacteria
- Cocci = spherical
- Bacilli = rod shaped
- Spirilli = helical
What is cyanobacteria?
- Photosynthetic bacteria found in extreme environments
- Many are toxic
- Can form symbiosis with sponges and unicellular flagellates
- They were involve in the oxygenation of the atmosphere
What are Archaea? Give an example.
A separate kingdom as share some similarities with eukaryotes
- Found in extreme environments such as deep ocean vents and hot springs
They derive energy in different ways:
- Can use oxidation of compounds containing sulfur rather than O2
- Some are methanogens - these derive their energy from organic compounds by combining them with hydrogen gas to form methane (e.g., this occurs in animal intestines)
One example is the Pyrococcus furiosus found in deep sea vents (contains Pfu-polymerase - this is important later)
What is the eukaryotic cytoskeleton function and structure?
The function of the cytoskeleton is to maintain cell shape and give cells motility
- Microfilaments -> composed of thin polymers of the globular protein actin (these Actin Filaments assemble and disassemble). These are components of muscle and used in cell movement and division (form the fronds that compose the cytoskeleton)
- Microtubules -> composed of large cylinders of globular tubulin dimers - these assemble and disassemble and are components of cilia and flagella (used in separating chromosomes during cell division - form centrioles)
- Intermediate filaments -> intermediate in size composed of fibrous proteins (e.g., keratin) rather than globular. These generally don’t disassemble once formed - allow the cell to be flexible
Components of an animal cell
- Lysosome (blobs that contain digestive enzymes to break down lipids, proteins, carbs, nucleic acids etc.
- Ribosomes (site of protein synthesis and composed of rRNA)
- Smooth Endoplasmic reticulum (synthesis of essential lipids; e.g., phospholipids and cholesterol)
- Rough Endoplasmic reticulum (has ribisomes attached an is involved in protein folding and transport)
- Nucleus (contains DNA, with a nuclear envelope with nuclear pores in, a nucleolus (making ribosomal subunits) inside a nucleoplasm)
- Cell membrane (a partially permeable membrane composed of a phospholipid bilayer - regulates transport to and from the cell)
- Mitochondrion (site of aerobic respiration)
- Cytoplasm
- Golgi apparatus (processes and packages lipids and proteins for cell export)
- Peroxisomes (carry out oxidative reactions)
- Centrosome (composed of two centrioles which are in turn composed of microtubules - used in cellular replication)
Which subcellular structures are found in plant cells which aren’t in animal cells?
- Plasmodesmata (in the cell call which allow communication with other algal and plant cells)
- Cell wall (extra structural support)
- Vacuole (maintain water balance)
- Chloroplasts (site of photosynthesis)
What are three energy transducing organelles found in eukaryotes?
- Mitochondria (has two membranes and two compartments (matrix and inter-membrane space), is the site of food molecule oxidation to produce ATP)
- Chloroplasts (3 membranes and 3 compartments, absorb light and use energy to produce carbs from CO2)
- Peroxisomes (oxidative reactions - fatty acid degradation and conversion of hydrogen peroxides to H20 and O2
All of these have membranes across which a gradient allows for energy synthesis
Which molecules compose carbohyrates?
- monosaccharides (glucose, galactose and fructose)
- disaccharides: sucrose (glucose + fructose), lactose (galactose + glucose), and maltose (glucose + glucose)
- polysaccharides (starch, cellulose etc.)
Monosaccharides are bound to each other via glycosidic bonds
What is the function of carbs
- Mechanical support (e.g., cellulose and starch)
- Energy storage - longterm (e.g., starch)
- Cell surface recognition (glycoproteins, glycolipids etc.)
What is the structure of DNA?
- Two long polymers composed of nucleotides
- Sugar and phosphate backbones which are bound with ester bonds, with nitrogenous bases bound to the 1’ C on the sugar
- Two strands run in opposite directions and are therefore “antiparallel”
- The strands are bound via hydrogen bonds between the nitrogenous bases
- The phosphate group is bound to the 5’ C of the below sugar and the 3’ C of the sugar above (hence the 3’ and 5’ ends)
What makes DNA able to be used across many different taxa?
- It is surprisingly consistent
- This is because it is very unreactive (so has stayed largely the same)
What is the difference between RNA and DNA?
- RNA is single stranded whilst DNA is double stranded
- RNA nucloetides contain ribose, DNA contains deoxyribose - lacks one O atom [these are the pentose sugars]
- RNA has the base Uracil in place of the Thymine found in DNA
Describe the structure and characteristics of nucleotides.
- Contain a nitrogenous base (A, G, C, T/U)
- Contain a pentose sugar (ribose has an extra O than deoxyribose)
- Phosphate groups (there can be none (known as a nucleoside), one (known as a nucleotide monophosphate), two (known as a nucleotide diphosphate), three (known as a nucleotide triphosphate) etc.
- Composed of benzene rings (alternating double and single bonds), which absorb light
