Eukaryotes Flashcards
What are the differences between eukaryotes and prokaryotes? (10)
What are the differences in the location of DNA between prokaryotes and eukaryotes? (2)
o Eukaryotes: located in nucleus with a double membrane
o Prokaryotes: concentrated in a region not membrane bound called nucleoid
What are the differences in the cytoplasm between prokaryotes and eukaryotes? (2)
o Eukaryotes have a variety of organelles of specialised form and function
o Prokaryotes have organized regions
True or false
Eukaryotes are larger and can carry out more functions than prokaryotes.
True
What are the similarities between eukaryotes and prokaryotes? (4)
Both have: > plasma membranes enclosing them > cytosol, > DNA > proteins
What are the parts of the endomembrane system? (7)
- Nuclear envelope
- ER (rough and smooth)
- Lysosomes
- Vesicles that bud off ER
- Golgi body
- Vesicles that bud off Golgi
- Plasma membrane
Eukaryotic cells have an elaborate and extensive internal membrane system. This divides the cell into compartments. What is compartmentalization?
Compartmentalization provides different local environments for specific metabolic reactions to occur
o Incompatible processes can occur at the same.
What are the functions of plasma membranes and organelle membranes?
Plasma membranes and organelle membranes also participate in the cell’s metabolic activities as well as a variety of functions based on the composition of the membranes.
How are membranes in the endomembrane system related?
Membranes in this system may be related through direct physical continuity, or by transfer of membrane segments (vesicles). However, the various membranes are not identical.
What does the nucleus contain?
The nucleus contains most of the genes in the eukaryote —> some found in mitochondria.
The nucleus is ___ in size.
5 micrometers
What does the nuclear envelope do?
The nuclear envelope encloses the nucleus, seperating its contents from cytoplasm.
What is the structure of the nuclear envelope? (3)
- Has a double membrane
- Each a lipid bilayer
- Contains pores for entry and exit of RNAs and proteins
What happens to DNA in the nucleus?
DNA is organised into chromsomes —> carries genetic information
What is the relation between DNA and chromosomes? (3)
- Chromsomes are made up of DNA strands wrapped around a core of proteins
- Together chromosomes form the chromatin network
- Chromosomes are only distinguishable during cell division
What happens in the nucleolus? (2)
- Synthesis of mRNA occurs
- Assembly of ribosomes
What are the overall functions of the nucleus? (2)
- Carries heriditary information
- Controls all the activities in the cell
What are the ribsomes?
Ribsomes are the protein factories of cells, made of mRNA and protein.
Is a ribsome an organelle?
No, as it does not contain a membrane.
Ribosomes aid in ____ synthesis.
protein
Ribosomes are either free (suspended in the ____) or bound (attached to outside of ___). The type of ribosome determines the functioning of the ____ created.
cytosol
ER
protein
What is the endoplasmic reticulum?
ER is an extensive network of membranes that accounts for half of the total membrane in eukaryotic cells.
- Endoplasmic—> ____ the cytoplasm
* Reticulum—>little _____.
outside
network
What does the ER consist of?
Consists of a network of membranous tubules and sacs called cisternae.
What is the function of the ER membrane?
ER membrane separates the internal compartment of the ER (lumen/cisternal space) from the cytosol.
ER is continuous with nuclear envelope, therefore, space between two membranes of envelope is continuous with _____.
lumen
Two distinct but connected regions of ER: (2)
o SmoothER—>smooth outer surface that lacks ribosomes
o RoughER—>rough outer surface studded with ribosomes
What is the function of the smooth ER?
- Synthesis of lipids (oils, phospholipids and steroids (and hormones)
o Made by enzymes of smooth ER
o Sex hormones produced as well as steroid of adrenal glands - Metabolism of carbohydrates
o Enzymes covert glycogen into glucose used in cellular respiration - Detoxification of poisons—>liver
- Stores calcium ions in muscle cells
o Aids in muscle contraction
How does the SER detoxify poisons? (3)
o Drug enters body, Smooth ER detoxifies it by adding a hydroxyl (OH) group onto drug, making it soluble, making it easier to be flushed from body
o Results in the proliferation of smooth ER—> large amounts of smooth ER produced—>faster right of detoxification
o Results in an increase in drug tolerance, therefore, higher doses required to achieve same effect
What is the function of the rough ER? (2)
• Synthesis of secretory proteins by ribosomes attached to rough ER
o Cell then secretes these proteins
o E.g. secretion of insulin protein by pancreas into bloodstream
• Membrane factory for cell
o Grows by adding membrane proteins and phospholipids to its own membrane
What happens to the secretary proteins that depart the ER?
• Secretory proteins depart from ER wrapped in membranes of vesicles that bud from the region called the transitional ER (these are known as transport vesicles) . Some of these vesicles travel to the Golgi body.
What happens at the golgi body?
• At the Golgi body products of the ER (such as proteins) are modified and stored before being sent to other destinations.
What does the golgi apparatus consist of?
Golgi apparatus consists of flattened membranous sacs (cisternae), looking like a stack. There are many stacks of Golgi present in cells that are specialized for secretion of proteins. Separation of internal space of cisternae from cytosol by membrane.
How do the membranes cisternae on either side of the stack differ? (2)
The membranes of cisternae on either side of the stack differ in thickness and molecular
composition
The two sides of a Golgi stack have distinct polarity and are known as the cis and trans regions. What is the cis region?
Cis = receiving end (usually closer to ER)
o Transport vesicles add their membranes and the contents of their lumen to the cis by fusing with Golgi membrane.
The two sides of a Golgi stack have distinct polarity and are known as the cis and trans regions. What is the trans region?
Trans = transport/shipping end
o Gives rise to vesicles that pinch off and travel to other sites
How are the products of the ER modified?
The products of ER are modified during the transition through Golgi body, from the cis to the trans ends
What is a lysosome?
A lysosome is a membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest macromolecules.
Where do lysosomal enzymes work best, and why?
• Lysosomal enzymes work best in acidic environments such as the one found in lysosomes
o If a lysosome bursts, the enzymes are inefficient due to the neural pH of cytosol
o Excessive leakage can destroy a cell by self digestion
Where are lysosomes made?
• Lysosomes and their contents are made by rough ER and then transferred to Golgi apparatus for processing
o Some arise from the budding off the trans face of the Golgi body
Explain the role of lysosomes in digestion. (2)
• Lysosomes carry out intercellular digestion in a variety of circumstances, for example during phagocytosis, the food vacuole fuses with the lysosome, whose enzymes digest the food
o Digestion products then move into the cytosol and are used as nutrients
o Human cells that carry out phagocytosis are white blood cells (macrophages)
What is autophagy?
Lysosomes also undergo a process known as autophagy—> where the cell’s own organic material is recycled
o Damaged organelles are fused with the lysosome where they are broken down and the products released back into the cytosol for reuse
o In this way cell constantly renews itself—> liver cells in humans
What is the case with inherited lysosomal storage disease, and provide an example? (2)
Inherited lysosomal storage disease lack functioning hydrolytic enzymes—> indigestible material interferes with cell activities
o Tay Sachs (non-functional hydrolytic enzymes – brain becomes impaired due to accumulation of lipids in cells)
What does the double layer of a mitchondrion consist of?
>Surrounded by a double layer—> -each made of a phospholipid belayer -outer membrane—>SMOOTH -inner membrane—>FOLDED (christae-large surface area)
What are the two internal components of a mitochondrion? (2)
> Divided into 2 components internally
- Inter membrane space
- Mitochondrial matrix
What does the mitochondrial matrix contain?
> Mitochondrial matrix contains many respiratory enzymes and mitochondrial DNA+Rbosomes
Provide the formula for energy change in mitochondria.
Energy change=
oxygen+ complex sugars—>ATP+carbon-dioxide
Chrloplast contain a green pigment called ____.
chlorophyll
What is the double membrane layer in the chlorplast divided by?
> double membrane layer divided by very narrow inter membrane space
What are thyalakoids? (3)
> inner flattened membranous sacs that are interconnected make the inner membranous system
Thylakoids stacked like poker chips into grana
These thylakoids/grana are surrounded by the liquid stromatolites
What do stromatolites contain? (3)
- chloroplast DNA
- Ribosomes
- Photosynthetic enzymes
What is the formula for energy change in chloroplasts?
> Energy change:
light energy—> chemical energy (sugar)
What are the similarities between chrloplasts and mitochondria? (5)
• Considered separate from endomembrane system—>no connected physically or by means of vesicles to endomembrane system
• Both organelles enclosed by membranes (at least two membranes)
• Contain their own DNA that encodes some of their proteins
• Semi-autonomous—>grow and reproduce within cell
• Covert energy to forms that the cells can use
- Mitochondria are the sites of cellular respiration, the metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, and other fuels
- Chloroplast are involved in photosynthesis—> solar into chemical energy
Movement of secretory proteins from the site of production to the
exterior of the cell. Describe this process. (4)
> made by ribosomes (rough ER)
transport system involves vesicles and motor proteins that are connected to the the cytoskeleton of the cell (required ATP molecules)
energised motor proteins and vesicles containing secretory protein monomers or fully constructed secretory proteins transport them via the cytoskeleton (microtubule transport routes)
once it is available; exocytosis may take place(large vesicles moving to the cell membrane attaching and integrating the membranes eventually allowing the secretory proteins or its monomers to the exterior of the cell
-mights stop off at the Golgi body first & then after modification will continue to be secreted
-Cells specialised for the synthesis and secretion of many proteins are often loaded with many Golgi bodies/complexes to finalise and ascertain accurate modifications & sorting.
