CELL Flashcards
Arrange from smallest to largest.
Tissues, organ system, cells, organs, organism
Cells
Tissues
Organs
Organ system
Organism
Smallest cell?
Sperm
Largest cell ?
Ovum
Longest cell?
Nerve
How does shape of RBC help?
Circular biconcave help move thru capillaries
How does nerve cell shape help?
Conduct nerve impulse from one point to another
Structures in eukaryotic cell? Eleven
Plasma membrane
Nucleus
Cytoplasm
Cytosol
ER
Golgi apparatus
Ribosome
Mitochondria
Lysosome
Cytoskeleton
Peroxisome
3 characteristics of plasma membrane ?
Thin
Elastic
Semi-permeable
Thickness of membrane ?
7nm
75-11-A*
2 Characteristics of plasma membrane ?
Lipid bilayer
Fluid mosaic model
2 Function of endosome ?
Sorting and delivery of internalized material from cell surface and transport of material from Glock to lysosome or vacuole
6 features of largest organelle ?
• Spherical dense body found in the centre of the cell
• Present in almost all cells except few (eg: mature RBC etc.)
• Most cells are uni-nucleated (exception - skeletal muscle cells)
• Double layered membrane covers the nucleus – nuclear membrane (envelope) with pores
• Filled with colourless liquid inside – nucleoplasm (karyoplasm)
• Nucleoplasm contains the nucleolus (non- membranous) and chromatin fibres
2 features of chromatin?
• Chromatin fibres are made up of deoxyribonucleic acid and protein histone
. Condense to form chromosome when abt to divide
What are genes and their function?
Stretches of DNA in chromosome that transfer hereditary info from one gen to next
4 functions of nucleus ?
- Control all cellular activities (metabolism, protein
synthesis, growth, cell division) - Nucleolus synthesizes RNA (ribosomal subunits) to constitute ribosomes – thus very prominent in cells actively synthesizing proteins
- Storage and transmission of hereditary information in genes
- DNA replication
What is ER?
• Network of tubular and vesicular structures interconnected with one another
• ER usually comprise more than half of the
membranous content of the cell
Two types of ER and characteristics ?
Twotypes:
- Smooth - no ribosomes attached
- Rough - with ribosomes - lies immediately next to the cell nucleus, and its membrane is continuous with the outer membrane of the nuclear envelope to inc. efficiency of translation
What is function of RER?
RER:
• Synthesize secretory (glycoproteins) & membrane proteins (prominent in liver cells)
• Involved in protein folding
Function of SER?
- SER:
• Synthesis lipids for cell membrane (phospholipids), synthesis of cholesterol (partial)
• In liver-detoxify drugs and poisons,ethanol oxidation
• In muscle cells – store calcium ions (sarcoplasmic reticulum)
Describe structure of Golgi body ?
Formed by stacks of 5-8 membranous sacs
• These sacs are usually flattened - called cisternae
• Has 2 ends:
- cis face situated near the ER and trans face situated near the cell membrane
Cis – receives proteins from ER
Medial – post translational modifications of proteins
Trans – modified proteins are sorted & packaged for delivery
4 functions of Golgi ?
• Functions:
- Modifies (add fatty acids or phosphate gps, remove monosaccharides, cleave oligosaccharides), sorts & packs materials synthesized in the cell
- Delivers synthesized materials to various targets inside (lysosomes) and outside (exocytosis) the cell (Cell membrane)
- Produces secretory vesicles (eg: secretion of insulin by beta cells of pancreas, trypsinogen secretion by pancreatic acinar cells)
- Forms plasma membrane and lysosomes
What is a lysosome?
Small, spherical, single membrane sacs
• Acidic compartments (acid hydrolases;pH5)
• Filled. with hydrolytic enzymes(proteins) which
are received from RER
Where are lysosomes found?
• Abundant in macrophages
• Found throughout the cytoplasm
4 functions of lysosome and anything extra ?
• Digest foreign particles (viruses, bacteria) and helps to
protect the cell
• Degrade worn out organelles
• In dead cells - autolysis - autophagy
• Help digest large molecules (proteins, DNA, RNA, lipids)
- Endocytic vesicles (= endosome) stuff coming from outside cell)
- Phagosomes (bacteria etc containing vesicles)
How to lysosomes work ?
fuse with lysosomes (primary) to form secondary lysosome, digest material and hydrolysed products are used by the cell (Recycling)
Describe structure of mitochondria ?
• Small,round/oval shaped bound by TWO membranes – inner & outer
• Outer membrane - smooth
• Inner membrane – folded & forms the cristae
(contains enzymes of ETC) increase surface area
• Inner cavity – matrix filled with many enzymes
• Contains own DNA which produce many enzymes
• Number – vary per cell - mature RBC – Not present / Liver & Muscle cells large no.)
10 functions of mitochondria ?
- Synthesize ATP (energy) - ETC, Citric acid cycle enzymes
- Convert ammonia to urea (part - early stage of urea cycle enzymes – only in liver)
- Heme synthesis (part)
- Beta oxidation (triglyceride breakdown)
- Ketone body synthesis
- Glucose synthesis (part)
- Pyrimidine synthesis (part)
- Cytochrome P-450 in inner mitochondrial membrane - steroid synthesis
- Apoptosis (programmed cell death)
- Hormonal signaling
Structure of peroxisome and where to find?
Found in cytoplasm
Spherical in plants
Different shapes and sizes in animals
Has single membrane that is lipoprotein in nature
3 Function of peroxisome ?
Contains enzymes ( catalase to convert h202 to h2o and o2,oxidase )
Oxidation of bio molecules ex. Lipids to h2o2
Synthesize plasmogens ( a membrane lipid )
Function of ribosome ?
Make protein by binding to mRNA and lets tRNA enter and add amino acids
Describe cytoplasm ?
Jelly like viscous material
70% of cell volume
Contains organelles
Contain clear liquid portion CYTOSOL and various particles ( proteins (like enzymes), CHO , lipids, inorganic ions, salts)
8 pathways in Cytosol due to enzymes it carries?
- Glycolysis
- Fatty acid synthesis
- Cholesterol synthesis
- Urea cycle (part)
- Heme synthesis (part)
- Pyrimidine synthesis (part)
- Purine synthesis
- Glucose synthesis
What is cytoskeleton
Network of Interlinking protein filaments present in cytoplasm
What is cytoskeleton made of?
protein fibres (help the cells move & maintain shape)
• Includes:
– Microtubules
– Microfilaments
– Intermediate filaments
Describe structure of microtubule .
Hollow structures formed from protein subunits (tubulin dimer, alpha and beta dimers )
3 functions of microtubule
1.Helps to support cytoplasm of cells
2.Assist in cell division (mitotic spindle)
3. Intracellular transport
Structure of microfilament ?
Small fibrils of protein subunits (globular actin)
3 function of micro filaments?
Involved in cellular movement
cell shape
muscle contraction
Structure of intermediate filament ?
fibrils formed from protein subunits by intertwining
• Are smaller in diameter than microtubules but larger than microfilaments
7 functions of intermediate filaments ?
- provide mechanical support to cell
- Determines the shape
of the cell - Locomotion of the cell itself
- Give structural strength to the cell
- Responsible for sub- cellular movements
- Facilitate movement of chromosomes
- create cell cohesion by prevent fracture of epithelial cell under tension
Name 2 lysosomal diseases
Tay-Sachs disease
Pompe disease
What causes Tay-Sachs ?
Deficiency of enzyme (hexosaminidase A)
Effect of Tay-Sachs ?
results in excessive accumulation of lipids known as gangliosides in brain & nerve cells.
• Excess fat accumulation causes lysosmal damage, cell destruction and damage to surrounding tissues.
• This abnormal accumulation of gangliosides cause progressive dysfunction of central nervous system ( neurons in brain and spinal cord).
Fatal in children
What is pompe disease ?
Pompe disease (1 in every 40,000 births) is an inherited often fatal disorder that affects the heart and skeletal muscles.
• Deficiency/lack of acid alpha-glucosidase (GAA) which break down glycogen to glucose
• excessive amounts of lysosomal glycogen accumulate in body
Effect of pompe disease ?
Impair function of skeletal and heart muscles most
What is mitochondrial disease?
• Associated with reduction in production of energy
• Brain requires large quantities of energy & sufficient energy is needed for neurons to function properly
Effect of mitochondrial disease ?
• Deficiency of energy may lead to impaired capabilities (exercise intolerance, etc) and Autism
