Eukaryotic Cells Flashcards
What does eukaryotic mean?
Cells contain a “true nucleus” surrounded by nuclear envelope and other membrane bound organelles
Contains DNA (genetic code)
Nucleus functions (three)
Contains generic material (DNA in chromosomes)
Controls cell activities
Manufactures ribosomal RNA and assembles ribosomes
Nuclear envelope functions (two)
Controls entry and exit of substances
Contains reactions inside the nucleus
Nuclear pores functions (one)
Allows passage of large molecules such as mRNA out of nucleus
Nucleolus function
rRNA manufactured and ribosomes assembled here
What does protein bound mean?
The DNA is wound around proteins called histones
What is the structure of ribosomes?
Small
Made up of two sub units of protein and rRNA
What is the size of ribosomes in cytoplasm in eukaryotic cells?
80 s (subunits)
What is the size of ribosomes in prokaryotic cells?
70 s
Function of ribosomes
Site of protein synthesis
Function of plasma membrane
Selectively permeable and so it regulates what can enter/leave the cell
What is the cell theory proposed in 1839 by Schleiden and Schwann?
Cell is the most basic unit of life
All living organisms are composed of one or more cells
All cells arise from existing living cells
Endoplasmic reticulum structure
Folded membranes (cisternae)
Rough- ribosomes on it
Rough endoplasmic reticulum function
Large surface area that processes proteins from ribosomes
Pathway for transport of materials (proteins)
Smooth endoplasmic reticulum functions
Synthesis, stores and transports lipids
Synthesis, stores and transports carbohydrates
What types of cells will contain a lot of rough er?
Cells that need a lot of protein
e.g. Muscle, intestinal epidermis
How many cistenae will you find in one cell?
Only one
Why does there sometimes appear to be more than one cisternae?
If the cell is cut transfersly (cross-section) then a 2D
Golgi apparatus structure
Folded membranes making cisternae
Golgi apparatus functions
Adds carbohydrates to proteins to form glycoproteins
Produces secretory enzymes
Proteins processed, packaged and modified
Forms lysosomes
Golgi vesicle structure
Small rounded hollow structures
Golgi vesicle function
Transport substances to and from the Golgi apparatus (lipids and proteins)
What produces lysosomes?
Golgi apparatus
What size are lysosomes?
Medium size (up to 1um)
Lysosomes structure
Bags of digestive enzymes (can contain 50 different enzymes)
Lysosomes functions
Hydrolyse phagocytic cells
Completely breaks down dead cells
Release any useful materials that can be recycled
Mitochondria structure
Double membrane, inner membrane called cristae
Fluid centre called the mitochondrial matrix
Loop of mitochondria DNA
Mitochondria function
Site of aerobic respiration
Site of ATP production
Why do mitochondria sometimes appear to be round?
Orientation when cut - longitidinal / transverse
What is respiration?
Release of energy from glucose
Which molecule is used for energy in cells?
ATP
Which types of cells have many mitochondria (need lots of energy)?
Metabolically active cells e.g. Muscle cells
Chloroplasts structure
Double membrane
Contains thylakoids (folded membranes embedded with pigment)
Fluid filled stroma contains enzymes for photosynthesis
Chloroplast function
Site of photosynthesis
How are chloroplasts adapted for there function?
Grand - large surface area for attachment of chlorophyllneeded for the first stage of photosynthesis
Stroma - contains enzymes for second stage of photosynthesis
DNA and ribosomes - for quick synthesis of proteins for photosynthesis
Plants have chloroplasts. Can you name another type of organism that contains chloroplasts?
Algae
Vacuole structure
Filled with fluid surrounded by a single membrane called a tonoplast
Vacuole functions
Make cells turgid and therefore provide support
Temporary store of sugars and amino acids
Pigments may colour petals to attract pollinators
What cells have cell walls?
Plant and fungi cells
Cell wall structure (in plants)
Made of cellulose microfibrils
Cell wall function
Mechanical strength
Allows water to more along it contributing to water movement through the pants
What are fungi cell walls made out of?
Chitin, glycan and glycoproteins
What are algae cell walls made of?
Cellulose and/or glycoproteins
What is cell fractionation?
Cells have to be broken up and the different organelles are separated out
What are the 4 steps of homogenisation?
-Tissue chopped up and placed in isotonic buffer solution at 2°to 4°C
- buffered tissue in blender and blended
-This breaks up the cells and leases the organellesfrom the cells
-then filtered to remove complete cells
Why does the solution have to be cold in homogenisation?
Reduces enzyme activity
What are the two stages of cell fractionation?
Homogenisation and ultra-centrifugation
Why is a solution of the same water potential as the tissue used in homogenisation?
Prevents organelles from bursting/ shrinking due to osmotic effects
Why is the solution buffered in homogenisation?
Maintains a constant ph
What is ultracentrifugation?
The heavy organelles will fall to the bottom first in the sediment leaving the clear supernatant which will be removed and re-spun for longer and faster
