Protein Synthesis PDF

Protein Synthesis (2 of 10) DNA information is coded into a sequence of bases A sequence of three bases (triplet) codes for an amino acid For example, a DNA sequence of AAA specifies the amino acid phenylalanine...

Protein Synthesis (2 of 10) DNA information is coded into a sequence of bases A sequence of three bases (triplet) codes for an amino acid For example, a DNA sequence of AAA specifies the amino acid phenylalanine Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Protein Synthesis (3 of 10) The role of DNA – Most ribosomes, the manufacturing sites of proteins, are located in the cytoplasm – DNA never leaves the nucleus in interphase cells – DNA requires a decoder and a messenger to carry instructions to build proteins to ribosomes – Both the decoder and messenger functions are carried out by RNA (ribonucleic acid) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Protein Synthesis (4 of 10) How does RNA differ from DNA? – RNA is single-stranded – RNA contains ribose sugar instead of deoxyribose – RNA contains uracil (U) base instead of thymine (T) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Protein Synthesis (5 of 10) Three varieties of RNA – Ribosomal RNA (rRNA): Helps form the ribosomes, where proteins are built – Messenger RNA (mRNA): Carries the instructions for building a protein from the nucleus to the ribosome – Transfer RNA (tRNA): Escorts appropriate amino acids to the ribosome for building the protein Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Protein Synthesis (6 of 10) Protein synthesis involves two major phases: – Transcription – Translation We will detail these two phases next Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Protein Synthesis (7 of 10) Transcription – Transfer of information from DNA’s base sequence to the complementary base sequence of mRNA – DNA is the template for transcription; mRNA is the product – Each DNA triplet corresponds to an mRNA codon – If DNA sequence is AAT-CGT-TCG, then the mRNA corresponding codons are UUA-GCA-AGC Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.16 Protein Synthesis Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Protein Synthesis (8 of 10) Translation – Base sequence of nucleic acid is translated to an amino acid sequence; amino acids are the building blocks of proteins – Occurs in the cytoplasm and involves three major varieties of RNA Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Protein Synthesis (9 of 10) Translation – Steps correspond to Figure 3.16 (step 1 covers transcription) ▪ Step 2: mRNA leaves nucleus and attaches to ribosome, and translation begins ▪ Step 3: incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by temporarily binding its anticodon to the codon Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.16 Protein Synthesis (1 of 5) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.16 Protein Synthesis (2 of 5) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Protein Synthesis (10 of 10) Translation – Steps correspond to Figure 3.16 ▪ Step 4: as the ribosome moves along the mRNA, a new amino acid is added to the growing protein chain ▪ Step 5: released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.16 Protein Synthesis (3 of 5) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.16 Protein Synthesis (4 of 5) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.16 Protein Synthesis (5 of 5) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Concept Link 3 Recall that the joining of amino acids by the ribosome into peptide bonds is the result of dehydration synthesis reactions (Chapter 2, p. 63). To make room for the new peptide bond, water (H2O) must be removed. A hydrogen atom is removed from one amino acid, and a hydroxyl group (OH) is removed from the other. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  II Tissues Part : Body Two Tissues – Groups of cells with similar structure and function – Four primary types: 1. Epithelial tissue (epithelium) 2. Connective tissue 3. Muscle tissue 4. Nervous tissue Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (1 of 14) Locations: – Body coverings – Body linings – Glandular tissue Functions: – Protection – Absorption – Filtration – Secretion Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (2 of 14) Hallmarks of epithelial tissues: – Cover and line body surfaces – Often form sheets with one free surface, the apical surface, and an anchored surface, the basement membrane – Avascular (no blood supply) – Regenerate easily if well nourished Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (3 of 14) Classification of epithelia – Number of cell layers ▪ Simple—one layer ▪ Stratified—more than one layer – Shape of cells ▪ Squamous—flattened, like fish scales ▪ Cuboidal—cube-shaped, like dice ▪ Columnar—shaped like columns Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.17a Classification and Functions of Epithelia Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.17b Classification and Functions of Epithelia Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.17c Classification and Functions of Epithelia Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (4 of 14) Simple epithelia – Functions in absorption, secretion, and filtration – Very thin (so not suited for protection) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (5 of 14) Simple squamous epithelium – Single layer of flat cells – Locations—usually forms membranes ▪ Lines air sacs of the lungs ▪ Forms walls of capillaries ▪ Forms serous membranes (serosae) that line and cover organs in ventral cavity – Functions in filtration or diffusion Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.18a Types of Epithelia and Examples of Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (6 of 14) Simple cuboidal epithelium – Single layer of cubelike cells – Locations ▪ Common in glands and their ducts ▪ Forms walls of kidney tubules ▪ Covers the surface of ovaries Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.18b Types of Epithelia and Examples of Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (7 of 14) Simple columnar epithelium – Single layer of tall cells ▪ Goblet cells secrete mucus – Locations ▪ Lining of the digestive tract from stomach to anus ▪ Mucous membranes (mucosae) line body cavities opening to the exterior Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.18c Types of Epithelia and Examples of Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (8 of 14) Pseudostratified columnar epithelium – All cells rest on a basement membrane – Single layer, but some cells are shorter than others giving a false (pseudo) impression of stratification – Location: respiratory tract, where it is ciliated and known as pseudostratified ciliated columnar epithelium – Functions in absorption or secretion Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.18d Types of Epithelia and Examples of Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (9 of 14) Stratified epithelia – Consist of two or more cell layers – Function primarily in protection Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (10 of 14) Stratified squamous epithelium – Most common stratified epithelium – Named for cells present at the free (apical) surface, which are squamous – Functions as a protective covering where friction is common – Locations—lining of the: ▪ Skin (outer portion) ▪ Mouth ▪ Esophagus Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.18e Types of Epithelia and Examples of Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (11 of 14) Stratified cuboidal epithelium—two layers of cuboidal cells Stratified columnar epithelium—surface cells are columnar, and cells underneath vary in size and shape Stratified cuboidal and columnar – Rare in human body – Found mainly in ducts of large glands Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (12 of 14) Transitional epithelium – Composed of modified stratified squamous epithelium – Shape of cells depends upon the amount of stretching – Functions in stretching and the ability to return to normal shape – Location: lining of urinary system organs Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.18f Types of Epithelia and Examples of Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (13 of 14) Glandular epithelia – One or more cells responsible for secreting a particular product – Secretions contain protein molecules in an aqueous (water-based) fluid – Secretion is an active process Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Tissue (14 of 14) Two major gland types develop from epithelial sheets – Endocrine glands ▪ Ductless; secretions (hormones) diffuse into blood vessels ▪ Examples include thyroid, adrenals, and pituitary – Exocrine glands ▪ Secretions empty through ducts to the epithelial surface ▪ Include sweat and oil glands, liver, and pancreas (these are both internal and external types of glands) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (1 of 14) Found everywhere in the body to connect body parts Includes the most abundant and widely distributed tissues Functions – Protecting – Supporting – Cushioning – Insulating Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (2 of 14) Characteristics of connective tissue – Variations in blood supply ▪ Some tissue types are well vascularized ▪ Some have a poor blood supply or are avascular – Extracellular matrix ▪ Nonliving material that surrounds living cells Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (3 of 14) Two main elements of the extracellular matrix 1. Ground substance—mostly water, along with adhesion proteins and polysaccharide molecules 2. Fibers ▪ Collagen (white) fibers ▪ Elastic (yellow) fibers ▪ Reticular fibers (a type of collagen) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (4 of 14) Types of connective tissue from most rigid to softest, or most fluid: – Bone – Cartilage – Dense connective tissue – Loose connective tissue – Blood Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (5 of 14) Bone (osseous tissue) – Composed of: ▪ Osteocytes (bone cells) sitting in lacunae (cavities) ▪ Hard matrix of calcium salts ▪ Large numbers of collagen fibers – Functions to protect and support the body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.19a Connective Tissues and Their Common Body Locations Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (6 of 14) Cartilage – Less hard and more flexible than bone – Found in only a few places in the body – Chondrocyte (cartilage cell) is the major cell type – Types ▪ Hyaline cartilage ▪ Fibrocartilage ▪ Elastic cartilage Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (7 of 14) Hyaline cartilage – Most widespread type of cartilage – Abundant collagen fibers hidden by a glassy, rubbery matrix – Locations ▪ Trachea ▪ Attaches ribs to the breastbone ▪ Covers ends of long bones ▪ Entire fetal skeleton prior to birth ▪ Epiphyseal (growth) plates in long bones Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.19b Connective Tissues and Their Common Body Locations Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (8 of 14) Elastic cartilage (not pictured) – Provides elasticity – Location: supports the external ear Fibrocartilage – Highly compressible – Location: forms cushionlike discs between vertebrae of the spinal column Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.19c Connective Tissues and Their Common Body Locations Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (9 of 14) Dense connective tissue (dense regular fibrous tissue) – Main matrix element is collagen fiber – Fibroblasts are cells that make fibers – Locations ▪ Tendons—attach skeletal muscle to bone ▪ Ligaments—attach bone to bone at joints and are more elastic than tendons Dense connective tissue (dense irregular fibrous tissue) – Dermis—lower layers of the skin Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.19d Connective Tissues and Their Common Body Locations Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (10 of 14) Loose connective tissue – Softer, have more cells and fewer fibers than other connective tissues (except blood) – Types ▪ Areolar ▪ Adipose ▪ Reticular Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (11 of 14) Areolar connective tissue – Most widely distributed connective tissue – Soft, pliable tissue like “cobwebs” – Functions as a universal packing tissue and “glue” to hold organs in place – Layer of areolar tissue called lamina propria underlies all membranes – All fiber types form a loose network – Can soak up excess fluid (causes edema) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.19e Connective Tissues and Their Common Body Locations Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (12 of 14) Adipose connective tissue – An areolar tissue in which adipose (fat) cells dominate – Functions ▪ Insulates the body ▪ Protects some organs ▪ Serves as a site of fuel storage – Locations ▪ Subcutaneous tissue beneath the skin ▪ Protects organs, such as the kidneys ▪ Fat “depots” include hips, breasts, and belly Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.19f Connective Tissues and Their Common Body Locations Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (13 of 14) Reticular connective tissue – Delicate network of interwoven fibers with reticular cells (like fibroblasts) – Forms stroma (internal framework) of organs which can support free blood cells (largely lymphocytes) – Locations ▪ Lymph nodes ▪ Spleen ▪ Bone marrow Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.19g Connective Tissues and Their Common Body Locations Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Connective Tissue (14 of 14) Blood (vascular tissue) – Blood cells surrounded by fluid matrix known as blood plasma – Soluble fibers are visible only during clotting – Functions as the transport vehicle for the cardiovascular system, carrying: ▪ Nutrients ▪ Wastes ▪ Respiratory gases Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.19h Connective Tissues and Their Common Body Locations Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Muscle Tissue (1 of 4) Muscle tissue contracts, or shortens, to produce movement – Muscle tissue is irritable (able to respond to stimuli) Three types of muscle tissue 1. Skeletal 2. Cardiac 3. Smooth Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Muscle Tissue (2 of 4) Skeletal muscle tissue – Packaged by connective tissue sheets into skeletal muscles, which are attached to the skeleton and pull on bones or skin – Voluntarily (consciously) controlled – Produces gross body movements or facial expressions – Characteristics of skeletal muscle cells ▪ Striations (stripes) ▪ Multinucleate (more than one nucleus) ▪ Long, cylindrical shape Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.20a Types of Muscle Tissue and Their Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Muscle Tissue (3 of 4) Cardiac muscle tissue – Involuntarily controlled – Found only in the heart – Pumps blood through blood vessels – Characteristics of cardiac muscle cells ▪ Striations ▪ One nucleus per cell ▪ Short, branching cells ▪ Intercalated discs contain gap junctions to connect cells together Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.20b Types of Muscle Tissue and Their Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Muscle Tissue (4 of 4) Smooth (visceral) muscle tissue – Involuntarily controlled – Found in walls of hollow organs such as stomach, uterus, and blood vessels – Peristalsis, a wavelike motion, is a typical activity – Characteristics of smooth muscle cells ▪ No visible striations ▪ One nucleus per cell ▪ Spindle-shaped cells Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.20c Types of Muscle Tissue and Their Common Locations in the Body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Nervous Tissue Function is to receive and conduct electrochemical impulses to and from body parts – Irritability – Conductivity Composed of neurons and nerve support cells – Support cells called neuroglia insulate, protect, and support neurons Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.21 Nervous Tissue Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Summary of Tissues Figure 3.22 summarizes the tissue types and functions in the body Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 3.22 Summary of the Major Functions, Characteristics, and Body Locations of the Four Tissue Types: Epithelial, Connective, Muscle, and Nervous Tissues Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Tissue Repair (Wound Healing) (1 of 5) Tissue repair (wound healing) occurs in two ways: 1. Regeneration ▪ Replacement of destroyed tissue by the same kind of cells 2. Fibrosis ▪ Repair by dense (fibrous) connective tissue (scar tissue) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Tissue Repair (Wound Healing) (2 of 5) Whether regeneration or fibrosis occurs depends on: 1. Type of tissue damaged 2. Severity of the injury Clean cuts (incisions) heal more successfully than ragged tears of the tissue Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Tissue Repair (Wound Healing) (3 of 5) Events of tissue repair – Inflammation sets the stage ▪ Capillaries become very permeable ▪ Clotting proteins migrate into the area from the bloodstream ▪ A clot walls off the injured area – Granulation tissue forms ▪ Growth of new capillaries ▪ Phagocytes dispose of blood clot and fibroblasts ▪ Rebuild collagen fibers Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Tissue Repair (Wound Healing) (4 of 5) Events of tissue repair – Regeneration and fibrosis effect permanent repair ▪ Scab detaches ▪ Whether scar is visible or invisible depends on severity of wound Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Tissue Repair (Wound Healing) (5 of 5) Tissues that regenerate easily – Epithelial tissue (skin and mucous membranes) – Fibrous connective tissues and bone Tissues that regenerate poorly – Skeletal muscle Tissues that are replaced largely with scar tissue – Cardiac muscle – Nervous tissue within the brain and spinal cord Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Developmental Aspects of Cells and Tissues (1 of 3) Growth through cell division continues through puberty Cell populations exposed to friction (such as epithelium) replace lost cells throughout life Connective tissue remains mitotic and forms repair (scar) tissue With some exceptions, muscle tissue becomes amitotic by the end of puberty Nervous tissue becomes amitotic shortly after birth Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Developmental Aspects of Cells and Tissues (2 of 3) Injury can severely handicap amitotic tissues The cause of aging is unknown, but chemical and physical insults, as well as genetic programming, have been proposed as possible causes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Developmental Aspects of Cells and Tissues (3 of 3) Neoplasms, both benign and cancerous, represent abnormal cell masses in which normal controls on cell division are not working Hyperplasia (increase in size) of a tissue or organ may occur when tissue is strongly stimulated or irritated Atrophy (decrease in size) of a tissue or organ occurs when the organ is no longer stimulated normally Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.