m3.4.1 cell nucleus Flashcards
describe the structure of nuclear lamina
- adjacent to inner membrane
- made of fine network of lamins ( protein intermediate filaments )
list the function of nuclear lamina
- supports the nuclear envelope
- maintains position of nuclear pore
- organize contents in nucleus
state the mutations in gene coding that makes up the nuclear lamina
- progeria’s syndrome ( child aging rapidly, caused by change in gene )
- EDMD ( emery-dreifuss muscular dystrophy ) slowly causes weakness in the shoulders, upper arms, and calves.
describe structure of nuclear pore that takes up 10-30% of the nucleus surface
- pore complex ( ring-like arrangement )
- octaganal strutcure ( over 50 nm diameter )
- cytoplasmic fave has 8 subunits around the central zone ( 9nm diameter )
state the function of nuclear pore
to transport water soluble molecules across the nucleus
state examples of water soluble molecules that can be transported by nuclear pore
- DNA
- RIBOSOMES
- PROTEINS
- SIGNAL MOLECULES
- LIPIDS
- CARBOHYDRATES
What dissolves in nucleoplasm/karyoplasm
- nucleotides
- enzymes
during interphase, what exists in karyoplasm
chromatin fibres ( 200 nm )
differentiate between euchromatin and heterochromatin
- euchromatin lightly packed while heterochromatin tightly packed
- euchromatin has DNA transcribed while heterochromatin does not have DNA transcribe
- euchromatin found in active metabolically cells while heterochromatin found in inactive cells
where is the location of heterochromatin
periphery ( outer part ) of the nucleus
what is the function of heterochromatin due to its dense feature
- gene regulation
- protect chromosome integrity
- heavier/condenser chromatin
describe the structure of nucleolus
- 1 to 4 per cell nucleus
- got dense basophillic material in nucleoplasm
- dissapear during cell division, reappear postdivision
- appear at nucleolar organiser region
what is the function of nucleolus?
- works at specific region of chromosomes which transcribes rRNA
- rRNA found in other cytoplasmic organelles also known as ribosomes
- protein synthesis
- has same amount of proteins and RNA - DNA transcribes RNA in nucleolus
- to associate with proteins
- then forms ribosomes
describe the appearance of ENDOPLASMIC RETICULUM
- complex system that makes up 10% of the cell
- extends from nuclear envelope ( almost but not quite ) to the plasma membrane
- interconnecting channels expand to form CISTERNAE ( flattened discs )
what is the function of cisternae
- localizes the ER in the cytoplasmic areas ( puts it into function )
what is the function of rough ER
- protein synthesis
- transport proteins to GOLGI APPARATUS & other parts of the cell
list the 2 types of proteins involved in Rough ER
1.water soluble proteins ( enter lumen and cross the ER to be released elsewhere)
- prospective transmembrane proteins ( remain embedded in ER such as channel prot etc for selective transport )
what part of the nucleus is partially reformed from the nearby remnants of ER
nuclear envelope
describe the structure of SMOOTH ENDOPLASMIC RETICULUM
- no ribosomes ( no prot systhesis )
- well-developed in cells that secretes lipids & steroids and in liver cells
list the examples of cells that secrets steroid hormones
- adrenal cortex ( endogens )
- leydig cells ( testosterone )
- follicular cells ( progesterone, oestrogen )
what is the 2 function of Smooth ER in maintaining glucose level
- glycogenolysis
- gluconeogenesis
differentiate between glycogenolysis and gluconeogenesis
- glycogenolysis is rapid while gluconeogenesis is slow
- glycogenolysis occurs in mucles while gluconeogenesis occurs in kidney
- glycogenolysis breaks down glucose while gluconeogenesis produce glucose
state the similarities of glycogenolysis and gluconeogenesis
- both occurs in liver
- both SER has glucose-6-phosphatase
- BOTH coverts glucose-6-phosphatase into glucose ( to increase glucose level )
what is glycogenolysis
- glycogen degradation
- increase glucose level in body
- produce G6P in muscle cells
what is gluconeogenesis
the metabolic process by which organisms produce sugars (namely glucose) for catabolic reactions from non-carbohydrate precursors
list the functions of smooth ER
- lipid synthesis
- steroids synthesis and secretion
- detoxifcation of drugs
- metabolism of carbohydrates
- ca2+ accumulation in skeletal muscle cells ( sarcoplasmic reticulum )
what is sarcoplasmic reticulum
- complex network of SMOOTH ER
- transmits electrical impulse - store & release ca2+
- allows muscle contraction
describe the Smooth ER in the smooth/skeletal muscle cells
- specialised form of ER, only in smooth n skeletal muscle cells
- storage n release of ca2+
- under influence of exitable electrons
- plays a role in EXCITATION CONTRACTION COUPLING ( ECC )
What is ECC ( EXCITATION CONTRACTION COUPLING )
the rapid communication between electrical events in plasma memb in skeletal muscles & the ca2+ release which allows contraction
discuss the role of ER in lipid production
- synthesis lipids n cholesterol to form cell membrances
- in fat tissues, there are abundant of SER - secretes enzymes - forms lipid droplets - stores energy reserves in form of triacylglycerides
- synthesis steroid hormones
discuss the role of SER in detoxification
liver cells contains abundant SER - alot of enzymes along SER membrances
- breakdown toxic chemicals like carcinoges alcohol barbiturates into water-soluble products
- alchohol n drugs actually stimulates liver cells to produce more SER to increse detoxification rate
describe the structure of mitochondria
- size : 0.2-1nm
- diameter : 5-10nm
- smooth outer membrane n inner membrane ( cristae )
describe characteristics of mitochondria
- rod / sphere
- move around n not static
- very reactive in high metabolic activity area
Explain about the cristae in mitocondria ( the inner foldings )
- extend wall to wall or one part of the way
- tubular shaped
what is the function of cristae in mitochondria ?
- large TSA for chem reactions
- more no. cristae, more cell activity
describe the matrix of the mitochondria
- the interior of mito
- GOT ribosomes
- GOT non-chromosomal DNA ( 5-10 of it , 2-3nm diam )
list the function of the matrix
- manufacture own protein
- small number of proteins produced by mtDNA
- GOT enzymes from Kreb’s Cycle/citric acid cycle - converts energy in food to ATP energy
what is kreb’s cycle in simple words
series of chemical reaction to help breakdown n release energy stored in food
describe the function of mitochondria in ATP production
- got ATP SYNTHASE ENZYME used in OXIDATIVE PHOSPHORYLATION
- oxidative process uses OXYGEN to convert ADP+Pi —> ATP + h20
ATP
- high energybond for metabolic processes
- krebs / citric acid cycle
state the chemical equation of the oxidation process during ATP production
ADP+Pi —> ATP + h20
describe the ATP Synthase
- got f1 and f0 base
- part of respiratory assembly ( electron transport chain )
- forms transmembrane complex of 9 diff polypeptides on inner membrane
- The ATP synthase F1 portion synthesizes ATP from ADP + Pi.
- f1 subunit squeezes ADP + Pi until they form ATP, then releases the ATP tgt
difference between ATPase and ATP Synthase enzymes
ATPase - ADP TO ATP
ATP Synthase - ATP to ADP
what does ATP Synthase use to generate ATP to ADP and inorganic phosphate in mitochondria
ATP synthase uses the flow of HYDROGEN IONS through the enzyme and back into the matrix
to generate ADP TO ATP and inorganic phosphate in mitochondria
