BMS Exam 1 Flashcards
Describe the function of the rough endoplasmic reticulum
- Proteostasis –> Protein Homeostasis
- Ex. Biosynthesis, Maturation, Secretory Proteins
- Glycosylation, Disulfide Bone Formation, and Oligomerization –> with the help of chaperones
- Properly folded proteins are transported in vesicles to the Golgi
- Chaperones identify improperly folded proteins and facilitate degradation in the cytosol by proteasomes
- ONLY proteins with a signal sequence are moved into the RER
Function of Chaperones
Identify improperly folded proteins and facilitate degradation in the cytosol by proteasomes
Describe the function of the smooth endoplasmic reticulum
Cellular Detoxification – specifically in liver cells
- storage of calcium ions (sarcoplasmic reticulum in muscle cells)
3 types of protein coats used for receptor-mediated endocytosis
- COPI
- COPII
- Clathrin
Use for COPII
Transport from ER to Golgi
Use for COPI
Transport from Golgi to ER
Use for Clathrin
Transport to and from plasma membrane
How does the SNARE Complex aid in exocytosis of vesicles?
Synaptotagmin
- Calcium binding protein on vesicle activates SNARE Complex
- VAMP, Syntaxin, and SNAP-25 alpha helices wind together
- Vesicle is brought closer to and fuses with target membrane
- Releases cargo
3 types of cytoskeletons
- Intermediate Filaments
- Microtubules
- Actin Filaments
Function of Intermediate Filaments
Structural Only
Function of Microtubules
Structural & Transport
Long Distance Transport
Tube-like, made from dimers
Has Polarity: +end: membrane
-end: nucleus
Function of Actin Filaments
Structural & Transport
Short Distance Transport
Double Stranded; made of globular (G) actin
Has Polarity: +end: membrane
-end: nucleus
Types of Molecular Motor ATPases & Function
Kinesin - moves toward + end of microtubules
Dynein - moves toward - end on microtubules
Myosin V - moves towards the + end on F-actin
Myosin VI - moves towards the - end on F-actin
Steps Involved In The Functioning of The SNARE Complex
v-SNAREs (in vesicle; VAMP/Synaptobrevin) bind to t-SNAREs (in target membrane; Syntaxin/SNAP-25)
Both are types of proteins
Water is squeezed from membranes
Stalk formation
Hemi-fusion
Fusion
What type of cell junction permits transport?
Gap Junctions
What type of cell junction selectively seals?
Tight Junctions
What type of cell junctions offer mechanical support?
Anchoring Junctions
What type of cell junction?
- Connect cytoplasm to adjacent cells
- composed of connexins
- found in bone, cardiac, and muscle
Gap Junctions
What can be the result of dysfunctions in gap junctions?
Cardiac Arrythmias
Examples of where gap junctions are found
Bone, cardiac, muscle, etc.
What type of cell junction?
- Holds cells together and forms a near leak-proof intercellular seal
- composed of claudins
Tight Junctions
Examples of where tight junctions are found:
Epithelial tissue lining the digestive tract, nephron, etc.
Dysfunction of tight junctions can result in:
Cancers and inflammation
What type of cell junction?
- Connect cells to each other and the extracellular matrix
- classified based on location
- Lateral Surface: Adherens & desmosomes
- Basal Surface: Hemidesmosomes & Focal Adhesions
Anchoring Junctions
Types of Anchoring Junctions & their Properties
Adherens: Cadherins & Actin
Desmosomes: Cadherin & Intermediate Filaments
Hemidesmosomes: Integrins & Intermediate Filaments
Focal Adhesions: Integrins & Actins
3 types of interactions with water & their properties
- Hydrophilic - charged and polar
- Hydrophobic - uncharged and nonpolar
- Amphipathic - have regions that are BOTH hydrophobic and hydrophilic
What is the Central Dogma?
All the information that a cell needs for life in encoded in the DNA
What Process?
- Information in a DNA strand is copied into a mRNA
- Initiated by factors binding to a promoter region
Transcription
What Process?
- A protein is synthesized from the information contained in mRNA
- tRNA brings amino acid to the ribosome for the growing polypeptide chain
Translation
What happens in the Primary Protein Structure?
Sequence of a chain of amino acids
What happens during the Secondary Protein Structure?
Local folding of the polypeptide chain into helices or sheets
What happens during the Tertiary Protein Structure?
3-dimensional folding pattern of a protein due to side chain interactions
What happens during the Quaternary Protein Structure?
Protein consisting of more than one amino acid chain
3 Responses to Misfolded Proteins
- ER-Associated Degradation (ERAD) Pathway
- The Unfolded Protein Response (UPR)
- Autophagy
What is the ER-Associated Degradation Pathway?
Ubiquitin tagged proteins are degraded by proteosome
What is The Unfolded Protein Response?
Inhibits protein translation. Increases folding capacity of the ER by causing more chaperons to enter the ER.
What is Autophagy?
A recycling system
Layers of the Epidermis In Order (Top to Bottom)
- Stratum Corneum
- Stratum Lucidum
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale
Which part of the epidermis?
- Single layer of cuboidal mitotic stem cells that give rise to keratinocytes; few melanocytes
Stratum Basale
Which part of the epidermis?
- Spiny appearance due to desmosomes visible after processing (dehydration)
Stratum Spinosum
Which part of the epidermis?
- Keratohyalin granules present
Stratum Granulosum
Which part of the epidermis?
- Transparent and found only in thick skin
Stratum Lucidum
Which part of the epidermis?
- Thickest layer consisting of dead keratinocytes
Stratum Corneum
What cells are in the epidermis?
Keratinocytes, Merkel Cells, Langerhans Cells, Melanocytes
Function of Merkel Cells
Mechanoreceptors which are essential for detecting light touch
Function of Langerhans Cells
Immune cells (Epidermal Macrophages)
Function of Melanocytes
Produce the melanin which offers protection against UV-Radiations
2 Layers of the Dermis
- Papillary Layer
- Reticular Layer
Which part of the dermis?
- 20% of thickness
- Areolar connective tissue with collagen and elastic fibers
Papillary Layer
Which part of the dermis?
- 80% of thickness
- Dense irregular connective tissue
- Collagen fibers in this layer add strength and resiliency to the skin
- Elastin fibers provide stretch-recoil properties
Reticular Layer
Components of the Dermis & their Functions:
Arrector Pili Muscles - smooth muscle contraction –> goose bumps
Sebaceous Glands - secrete sebum that protects and lubricates skin & hair
Sweat Glands & Blood Vessels - regulate body temperature
What is the hypodermis composed of & function?
Adipose and Areolar Connective Tissue - anchors skin to underlying structures (mostly muscles)
Function of Adipose
Shock Absorber
Insulator - reduces heat loss
Energy Storage
3 Types of Burns and Their Properties
1st degree burn - epidermis is affected
2nd degree burn - epidermis and regions of the dermis are affected
3rd degree burn - epidermis, dermis, and hypodermis are all affected
Appearance and Location of Basal Cell Carcinoma
Appearance: Pearly Bump
Location: Stratum Basale/ Germinativum
Appearance & Location of Squamous Cell Carcinoma
Appearance: Rough, Scaly Patches, Can Bleed or Appear as Open Sores (Ulcerated)
Location: Stratum Spinosum/Stratum Granulosum (Cells With A Nucleus)
Location of Melanoma
Stratum Basale / Germinativum in the melanocyte
Characterization of Melanoma (ABCDE Rule)
Asymmetry - 2 side don’t match
Border - Irregular and Exhibits Indentations
Color - Black, Brown, Tan, sometimes Red or Blue
Diameter - Larger than 6mm
Evolving - Changing Appearance
Structural Unit of Compact Bone
Osteon
Where are osteocytes located in compact bone?
Lacunae
How and Why are Lacunae connected?
Connected by canaliculi to permit nutrients transport to osteocytes, waste removal, and communication between osteocytes (gap junctions)
Outer sheath that contains blood vessels, nerves, and lymphatic vessels that nourish compact bone
Periosteum
The membrane that line the medullary cavity
Endosteum
Where are lacunae and osteocytes found in spongy bone?
In trabeculae
What is the benefit of spaces in spongy bone?
Spaces make bones lighter so that muscles can move them more easily.
Function of Osteoclasts & Where Do They Originate From?
Originate from WBCs
Continually breaks down old bone
What would osteoblasts become under the right conditions?
It would become an osteocyte when trapped within the matrix
What is the progression of bone cells?
Osteogenic Cells - Osteoblasts - Osteocyte
What do osteogenic cells differentiate into?
Osteoblasts
2 Parts to Fetal Bone Formation & Development:
- Endochondral Ossification
- Intermembranous Ossification
- Mesenchymal Cells –> Chondrocytes
- Chondrocytes form matrix in hyaline cartilage
- Calcification of matrix = cell death
- Blood vessels invade the cavity, bringing osteogenic cells
- Bone develops
Endochondral Ossification
- Mesenchymal Cells –> Osteoblasts
- Osteoblasts gather in ossification center
- Osteoblasts secrete osteoid and calcium
- Calcified matrix traps osteoblasts and turn them into osteocytes
- Prescence of blood capillaries causes bones to form as trabeculae in the middle
- Surface bone tissue forms compact bone
Intermembranous Ossification
4 Ways Osteocytes Regulate Bone Formation vs. Bone Resorption:
- Osteoprotegerin (OPG)
- Receptor Activator for Nuclear Factor kB Ligand (RANKL)
- Receptor Activator for Nuclear Factor kB (RANK)
- Sclerostin (SOST)
5 Steps In Bone Remodeling:
- Origination
- Activation
- Resorption
- Formation
- Mineralization
What is an active remodeling site referred to as?
Basic Multicellular Unit (BMU)
What cell makes RANKL, OPG, and SOST?
Osteocytes
RANKL (osteocyte) - RANK (preosteoclast) Interaction
Promotes osteoclastogenesis
RANKL (osteocyte) - OPG (osteocyte) Interaction
Promotes Bone Formation
SOST Function?
Inhibits bone formation and activates bone resportion
Shape Classification of Bones:
Flat, Long, Sesamoid, Irregular, Short, Sutural
Functions of Skeletal System
Support, Movement, Protection, Mineral/Energy Storage, Hematopoiesis, Endocrine Function
Growth of Long Bones In Adults
Epiphyseal Side - cartilage is formed
Diaphyseal Side - cartilage is ossified
The tubular shaft that runs between the proximal and distal epiphysis
Diaphysis
Red Bone Marrow
Epiphysis
Yellow Bone Marrow
Diaphysis
Connects Epiphysis to Diaphysis
Metaphysis
4 Risk Factors For Osteoporosis
Early Menopause, Small Body Frame, History of Eating Disorders, Low Vitamin D
Tactile Corpuscle of Dermis
Meissner’s
