Midterm 1
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What are plant tissues composed of?
Eukaryotic cells (contain a nucleus)
What is the area between cells called and what is it made of
Plasmalemma aka the plasma membrane, composed of pectates (complex set of polysaccharides) – plant glue/cement
What aids in fruit ripening and why
the middle lamella – uses the enzyme pectinases to break down pectins which it is made of to produce a softer fruit
What is the Flavr Savr gene and why is it important
It decreases pectin produced in fruit (started off with a tomato) and allows farmers to harvest fruit later, therefore resulting in something with fuller flavour components and fully developed sugars. Never went to market due to consumer acceptance
How does the plasmalemma aka plasma membrane work
It is semi permeable meaning it is covered in pores that allow smaller things such as water through but not larger things such as organelles (has limitations)
What are the continum of living/non living organisms through the plasmalemma called?
Living: symplast (biotic) Nonliving: apoplast (abiotic)
What are the 3 components of the plasmalemma called and what are their compositions
lipids: 40% proteins: 40% carbs: 20%
What are lipids composed of
They are bilayers with polar heads and nonpolar fatty acid tails (heads out tails in) that are chemically stable - called a unit membrane
What are phospholipids and what do they look like?
They are the most common type of membrane lipid that contain a charged polar head with 2 hydrophobic hydrocarbon tails. • unsaturated: not all H’s present, creates kinks (crooked) • saturated: straight tail with all H’s present
What are the 2 most common glycolipids
glucose and galactose
Why are lipid molecules unique
Not covalently linked together so they are able to move around (bob, flex, rotate, flip flop)
What do enzymes do
They act as catalysts and transport metabolites (something made/used when body breaks down stuff) across the cell membrane
What is the optimal temperature for most plants
20 degrees
What occurs during chilling injury and how does it affect the plasma membrane?
When the temperature gets too cold, the inside of the membrane goes from a fluid liquid crystalline state to a solid gel phase. This in turn causes the membranes to leak, causing it to lose its ability to catabolize reactions and creates an imbalance in the organism - primary mechanism of injuring plant tissues
Why is fluidity important for membranes?
Enzymes no longer work (tertiary and quaternary structures are altered and can’t bind) when its not fluid enough causing the enzymes and proteins not to be able to move in the phospholipid matrix and to function properly (responsible for transport in and out of the cell and hormone binding and primary hormone effects)
Why is semi permeability important for plant tissues
When it becomes too permeable toxic metabolites (such as ethanol and acetaldehyde) are able to enter the plant, giving it an off flavour and it allows the plant to access what it needs and not what it doesn’t
What kind of bonds do low and high temp plants have
low: unsaturated (double bonds - kinks) high: saturated (straight tails)
What is the definition of critical temperature
the highest temp at which freezing injury to plant tissues can be detected (closest it gets to being damaged)
What is hardening off?
• plants raised in a greenhouse need to be acclimatized to cooler temperatures, lower humidity and increased air movement for about two to three weeks before they are planted outdoors. This ‘toughening up’ process is known as hardening off.
What is the nucleus?
It is surrounded by a porous, double membrane nuclear envelope containing chromosomes (DNA) and one or more nucleoli (dark masses made up of protein and nucleic acids – involved in rRNA synthesis)
What is the endoplasmic reticulum?
a 3D network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. It usually has ribosomes attached and is involved in protein and lipid synthesis.
What are the 2 types of ER?
rough: has ribosomes smooth: no ribosomes
What are mitochondria?
They are organelles surrounded by a double unit membrane that provide energy for the cell. - centers of respiration
Dictyosomes or Golgi apparatus
collect, process, and deliver proteins out of the cell