BMS Exam 1 Flashcards by Avery Abercrombie

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

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Function of Chaperones

Identify improperly folded proteins and facilitate degradation in the cytosol by proteasomes

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Describe the function of the smooth endoplasmic reticulum

Cellular Detoxification – specifically in liver cells
- storage of calcium ions (sarcoplasmic reticulum in muscle cells)

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3 types of protein coats used for receptor-mediated endocytosis

COPI
COPII
Clathrin

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Use for COPII

Transport from ER to Golgi

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Use for COPI

Transport from Golgi to ER

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Use for Clathrin

Transport to and from plasma membrane

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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

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3 types of cytoskeletons

Intermediate Filaments
Microtubules
Actin Filaments

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Function of Intermediate Filaments

Structural Only

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Function of Microtubules

Structural & Transport
Long Distance Transport
Tube-like, made from dimers
Has Polarity: +end: membrane
-end: nucleus

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Function of Actin Filaments

Structural & Transport
Short Distance Transport
Double Stranded; made of globular (G) actin
Has Polarity: +end: membrane
-end: nucleus

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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

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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

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What type of cell junction permits transport?

Gap Junctions

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What type of cell junction selectively seals?

Tight Junctions

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What type of cell junctions offer mechanical support?

Anchoring Junctions

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What type of cell junction?
- Connect cytoplasm to adjacent cells
- composed of connexins
- found in bone, cardiac, and muscle

Gap Junctions

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What can be the result of dysfunctions in gap junctions?

Cardiac Arrythmias

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Examples of where gap junctions are found

Bone, cardiac, muscle, etc.

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What type of cell junction?
- Holds cells together and forms a near leak-proof intercellular seal
- composed of claudins

Tight Junctions

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Examples of where tight junctions are found:

Epithelial tissue lining the digestive tract, nephron, etc.

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Dysfunction of tight junctions can result in:

Cancers and inflammation

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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

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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

1. Hydrophilic - charged and polar 2. Hydrophobic - uncharged and nonpolar 3. 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

1. ER-Associated Degradation (ERAD) Pathway 2. The Unfolded Protein Response (UPR) 2. 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)

1. Stratum Corneum 2. Stratum Lucidum 3. Stratum Granulosum 4. Stratum Spinosum 5. 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

1. Papillary Layer 2. 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:

1. Endochondral Ossification 2. 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:

1. Osteoprotegerin (OPG) 2. Receptor Activator for Nuclear Factor kB Ligand (RANKL) 3. Receptor Activator for Nuclear Factor kB (RANK) 2. Sclerostin (SOST)

5 Steps In Bone Remodeling:

1. Origination 2. Activation 3. Resorption 4. Formation 5. 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