EL 7-11 Flashcards
• What are the 7 structures that make up the end-membrane system?
Nuclear envelope, CM, ER, golgi apparatus, vesicles, vacuoles and lysosomes
• What is the function of the endomembrane system?
- synthesis
- transport
- modification
- metabolism
- detoxification
Describe ER
network of membranous sacs and tubes= cisternae
- rough= ribosomes, synthesis of secretory proteins, modification of proteins and transport via vesicles
- smooth= no ribosomes, synthesis of lipids, detoxification and storage of calcium ions
Describe ribosomes
- complex of mRNA and proteins
- 2 subunits
- protein synthesis
Describe golgi apparatus
- flattened membranous sacs stacked on top of one another
- modifies, packages and transports products from the ER
describe the distinct structural directionality of golgi apparatus
- Cis face= products enter from ER
- Trans face= gives off vesicles that travel to other sites
Describe vesicles and vacuoles
- Large vesicles= vacuoles
- derived from ER and golgi apparatus
- functions are transport, storage and water balance
Describe lysosomes
- sac containing hydrolytic enzymes
- function is intracellular digestion
Describe mitochondrion
-double membrane
-own DNA
-ATP production
-
Describe chloroplasts
- contains green pigment chlorophyll
- own DNA
- light into chemical energy via photosynthesis
Describe mitochondrion
- double membrane
- own DNA
- ATP production
• Describe the structure of a microtubule
- Hollow rods constructed from a globular protein called tubulin
- each tubulin protein is a dimer( a and b-tubulin)
- grow in length by adding tubulin dimers/ disassembling them
• What is the ability to grow and shrink called?
Dynamic instability
• What are the main functions of microtubules?
- maintaining cell shape
- Transport
- Cell motility
- chromosome movement
what are centrosomes and centrioles and centriole’s structure
centrosome is the microtubule organising center which contains 2 centrioles at right angles to each other
-each centriole has 9 sets of 3 microtubules
• What are the two motor proteins and towards what do each of them go?
- kinesis towards +
- dyneins towards -
• How do microtubules bend?
- Large motor proteins (dyneins) are attached along each outer microtubule
- Dynein walks along microtuble
what is the common structure of cillia and flagella?
Basal body
axoneme( 9+2. pattern)
• How do microtubules bend?
- Large motor proteins (dyneins) are attached along each outer microtubule
- Dynein walks along microtubule
what are the functions of microfilaments?
- maintenance of cell shape
- muscle contraction
- cytoplasmic streaming
- cell motility
- division of animal cells
• What are the 2 things that help with muscle contraction?
- Microfilaments
- Myosin
Describe the 5 step process of muscle contraction
1) the myosin head is bound to ATP and is in its low-energy configuration.
2) The myosin head hydrolyzes ATP to ADP and Pi (inorganic phosphate) and is in its high-energy configuration.
3) The myosin head binds to actin, forming a cross-bridge with the thin filament.
4) The myosin couples release of ADP and Pi to a power stroke that slides the thin filament along the myosin and returns the myosin head to a low-energy state.
5) Binding of a new molecule of ATP releases the myosin head from actin, and a new cycle begins.
what causes the shortening of the muscle cell?
the walking of myosin projections drives parallel myosin and actin filaments past each other so that the actin filaments approach each other in the middle. this shortens the cell.
How does actin microfilaments cause division of animal cells?
Cleavage furrow is caused by contractile ring of actin microfilaments, interaction between myosin and microfilaments cause ring to contract and helps pinch parent cell into 2 daughter cells
• Why is intermediate filaments more permanent than the others?
arent assembled and diassembled
what is the functions of intermediate filaments?
- Maintenance of cell shape
- anchorage of nucleus and other organelles
- helps cells function
• Why is intermediate filaments more permanent than the others?
arent assembled and disassembled
Why does cell specialization take place?
- different cells for different functions
what does cell specialization rely on?
gene expression
define stem cells
cells with unique ability to develop into specilised cell types in the body
what do stem cells do?
- can stay as unspecialised cells that can reproduce
or
-can differentiate into 1/more types of specialised cells
define stem cells
cells with unique ability to develop into specialised cell types in the body
Define Totipotent
can divide into all cell types in an organism
Define Pluripotent
can divide into most cell types but cannot develop into an entire organism on their own
Define Multipotent
have the capacity to self-renew by dividing and to develop into multiple specialised cells types present in a specific tissue/organ
Define cloning
Process of producing individuals with identical or vitually identical DNA either naturally/ artificially
what is cloning?
produces 1/more organisms that are genetically identical to the parent that donated the single cell
Define cloning
Process of producing individuals with identical or virtually identical DNA either naturally/ artificially
Describe this cloning process
Nuclear transplantation is a method in which the nucleus of a donor cell is relocated to a target cell that has had its nucleus removed
Provide atleast 3 reasons as to why we clone?
- Novelty, exotic animals…
- Research animals, identical experimental conditions
- increasing stem cells to treat diseases
• Any ethical issues?
- can cause loss of life
- human identity may be violated
- could be used to breed ‘better humans’
• Definition of epigenetics
study of heritable changes in gene expression that doesnt involve changes to the underlying DNA sequence
• Explain what happens in epigenetics?
- gene expression is influenced
- not permanent
define gene expression
process by which info encoded in a gene is used to direct the assembly of a protein molecule
• What are histones?
proteins around which DNA is wrapped in the nucleosome
• What is histone acetylation?
addition of an acetyl group to histone tail
what happens to a acetylated histone?
causes nucleosomes to become loosely packed exposing more sections of DNA.
what is an acetyl group?
a part of a molecule containing carbonyl and methyl group
How does histone acetylation affect transpiration and transpiration factors?
- nucleosomes less tightly packed=increased transpiration
- Transpiration factors bind to DNA=genes expressed/ turned on
• What is DNA methylation?
addition of methyl group to histone tails.
what happens to a methylated histone?
causes chromatin to become more condensed
How does histone methylation affect transpiration and transpiration factors?
- nucleosomes more tightly packed= reduced transpiration
- transpiration factors cant access DNA to bind= DNA is not expressed/ turned off
define transpiration factors
protein that controls rate of transpiration of genetic info from DNA to messenger RNA
What is common between both histone modifications?
- no change in DNA sequence
- still can be passed onto future generations
define epigentic inheritance
Can be passed on to future generations
