Cells & Histology Chapters 3-4

exons

( exons do specify amino acid sequence.) Coding segments of eukaryotic DNA.

Number the following 9 steps of protein synthesis

1. Transcription factor binds the promoter 2. RNA polymerase builds the mRNA transcript 3. The end of the gene is reached, and the pre-mRNA is released and then edited 4. mRNA exits the nucleus via a nuclear pore 5. mRNA and initiator tRNA bind the small ribosomal subunit 6. The small ribosomal subunit finds the start codon, and the large ribosomal subunit joins. 7. New tRNAs are brought into the A site successively, and the peptide chain of the tRNA in the P site is joined to the amino acid of the tRNA in the A site. 8. The stop codon is reached, and the polypeptide is released 9. The protein is folded and modified to become functional.

Which of the following best describes the arrangement of the main component of the plasma membrane? a. a monolayer of phospholipids with the phosphate heads facing the cytosol and the fatty acid tails facing the extracellular fluid b. a bilayer of phospholipids with the phosphate heads facing the cytosol and extracellular fluid, and the fatty acid tails facing one another

A bilayer of phospholipids with the phosphate heads facing the cytosol and extracellular fluid, and the fatty acid tails facing one another.

Compare and contrast unicellular gland and multicellular gland

A unicellular gland is single cell that produces and secretes its product. A multicellular gland is a group of cells that function together to produce and release a product.

4 different nucleotides in DNA

Adenine, Thymine, Guanine, Cytosine A T G C

Stage of mitosis in which the chromosomes move to opposite poles of the cell

Anaphase

Which of the following is not a basic function shared by all cells? a. Cell metabolism b. communication c. cell reproduction d. cell movement e. transport of substances through the cell

Cell movement

Certain diseases are transmitted via mitochondrial DNA. Which cell types do you think would be most affected by such diseases and why?

Cells with very high demand for ATP will be disproportionately affected by mitochondrial diseases. Examples include those of muscles, the nervous system, the liver, and the kidneys.

Explain how and why chromatin is condensed in the nucleus.

Chromatin is condensed during cell division by being coiled repeatedly around histone proteins. This enables precise division of the chromosomes into two complete sets when the cell divides.

Our somatic cells' DNA is distributed among 46 ______ in the nucleus

Chromosomes

Vitamin C is required for synthesis of collagen. Predict the effect that a vitamin C deficiency (scurvy disease) would have on bone tissue, dense regular collagenous connective tissue, dense irregular connective tissue, and cartilage.

Collagen fibers are an important component of all tissues listed, giving them strength and the ability to resist tension. On vitamin C deficiency, collagen synthesis is impaired, which leads to bone pain, and weakness, skin fragility, tooth loss, joint pain, and myriad other symptoms.

Describe the role of Collagen fibers in the ECM

Collagen fibers are very tough fibers that make a tissue resistant to tension and pressure

Explain how connective tissues differ form epithelial tissues in structure and function.

Connective tissues have ECM (extracellular matrix) as their main component, which allows them to serve their functions of binding and supporting. Epithelial tissue is composed of sheets of cells with little ECM, which enables it to form a barrier between the body and the external environment and between the organs and fluid-filled cavities.

Dermis, surround joints, organs

Dense irregular connective tissue

Large arteries, certain ligaments

Dense regular elastic tisse

Holecrine secretion vs. merocrine secretion

During holocrine secretion, product accumulates until the cell ruptures and releases its product. During merocrine secretion, the cell secretes its product by exocytosis.

What is the role of elastic fibers in the ECM?

Elastic fibers have the ability to be stretched and return to their original length, and so give a tissue the properties of distensibility and elasticity.

Compare and contrast enodcrine gland and exocrine gland

Endocrine glands release hormones into the bloodstream and contain no ducts. Exocrine glands release substances into a body cavity or the outside of the body through a duct.

Release of large substances from the cell through a vesicle

Exocytosis

Passive movement of solute across the plasma membrane via a channel or carrier protein

Facilitated diffusion

Endocytosis, exocytosis, muscle cell contraction, and cellular "crawling" are all mediated by intermediate filaments.

False: Endocystosis, exocytosis, muscle cell contraction, and cellular "crawling" are all mediated by actin filaments.

The cilia fond on sperm cells propel the cells through a liquid medium

False: the flagella found on sperm cells propel the cells through a liquid medium

True or false Actin filaments combine with myosin motor proteins to provide the cell with mechanical strength

False; Actin filaments combine with myosin motor proteins to provide the cell with MOVEMENT

During metaphase, the sister chromatids are pulled apart and the chromosomes moved to the opposite poles of the cell.

False; During anaphase, the sister chromatids are pulled apart and the chromosomes move to the opposite polls of the cell.

True or false During the S phase of the cell cycle, the cell stalls until conditions for division are more favorable

False; During the G zero phase of the cell cycle, the cell stalls until conditions for division are more favorable.

Intermediate filaments are ropelike structures composed of tubulin proteins

False; Intermediate filaments are ropelike structures composed of fibrous proteins.

Loose connective tissue features protein fibers as its primary component.

False; Loose connective tissue features ground substance as its primary component.

The overall structure of the plasma membrane is the mosaic with the components locked tightly in place.

False; The overall structure of the plasma membrane is a mosaic with the components moving fluidly within the membrane.

True or False Fibroblasts store lipids in a large inclusion in their cytoplasm.

False; adipocytes store lipids in a large inclusion in their cytoplasm.

Cholesterol provides the plasma membrane with stability in the face of changing ion concentrations.

False; cholesterol provides the plasma membrane with stability in the face of changing temperatures.

True or False Epithelial tissues is highly vascular

False; epithelial tissues is avascular

Fibrocartilage provides a smooth surface on which bones may articulate with little friction.

False; hyaline cartilage provides a smooth surface on which bones may articulate with little friction.

True or false Pseudostratified epithelium appears to be simple epithelium but is actually stratified

False; pseudostratified epithelium appears to be stratified but is actually simple spithelium.

Stratified epithelia are specialized to allow substances to cross their cells rapidly.

False; simple epithelia are specialized to allow substances to cross their cells rapidly.

The ECM of bone tissue consists exclusively of calcium phosphate crystals

False; the ECM of bone tissue consists of calcium phosphate crystals and an organic component.

The main enzyme that builds the new DNA strands during DNA synthesis is RNA synthetase

False; the main enzyme that builds the new DNA strands during DNA synthesis is DNA Polymerase

Initial growth phase of the cell cyle

G1

Whats the role of Glycosaminoglycans in the ECM?

Glycosaminoglycans create a concentration gradient to draw water into the ECM by osmosis and trap it there; this makes a tissue more resistant to compression.

Modifies, packages and sorts proteins

Golgi apparatus

Freely moveable joints

Hyaline cartilage

Second growth state of the cell cycle

Interphase; G2

A popular science fiction program once had an episode that featured an "intron virus" that "turned on" the introns in the genes, causing the synthesis of abnormal proteins. The episode may have been entertaining, but its premise had a large flaw about the nature of introns. What was the flaw?

Introns are noncoding DNA, meaning they they do not code for any protein in the human body. Even if a virus were to "activate" them, it wouldn't result in the production of a protein, as they do not code for anything. In addition, introns are removed from mRna transcripts before they are translated.

Genetic code

List of which amino acid is specified by each DNA triplet

Stage of the cell cycle in which the cell divides

M phase

Stage of mitosis in which the sister chromatids line up on the cell's equator

Metaphase

Synthesizes most of a cell's ATP

Mitochondrion

Predict what would happen if the mucous membranes of the body stopped secreting mucus or if they secreted excess mucus.

Mucus protects many tissues, including the airways and the gastrointestinal tract. Inadequate mucus would allow bacteria and other irritants to have easier access to these tissues and would put the digestive tract at risk from its own acid and enzymes. Too much mucus could interfere with both breathing and digestion, processes that depend on transporting gases or nutrients across the epithelium.

Epithelial tissues, many connective tissues, and smooth muscle tissue often heal by regeneration because their cells retain the capacity to divide by mitosis. __________ tissue and other types of muscle tissue generally repair by fibrosis because their cells usually are unable to undergo mitosis.

Nervous

______________ are the cells of nervous tissue that send and received messages, and _________ are the supporting cells of nervous tissue. A _____________ carries a nerve impulse toard a neuron cell body, and a _______ carries a nerve impulse away form a neuron cell body.

Neurons; neuroglia; dendrite; axon

Introns

Noncoding segments of nucleic acid that lie between coding sequences. Copied introns in the pre-mRNA must be removed and the exons then splice together. this is called RNA processing; when complete, mRNA exits nucleus through nuclear pore; enters cytosol, ready for translation into protein.

Movement of solvent from a solution of lower solute concentration to a solution of higher solute concentration

Osmosis

What is the primary difference between active transport processes and passive transport processes?

Passive transport processes require no expenditure of energy by the cell. Active transport processes require energy expenditure in the form of ATP

Contains enzymes that oxidize toxins and fatty acids

Peroxisome

Type of endocytosis in which a large particle is ingested.

Phagocytosis.

Type of endocytosis in which ECF is brought into the cell in a protei-coated pit

Pinocytosis

Transport across the plasma membrane against the concentration gradient via direct use of energy from ATP

Primary active transport

Transcription Elongation

Process where RNA polymerase covalently bonds complementary (to DNA template) nucleotides to growing mRNA molecule

What is the role of proteoglycans in the ECM?

Proteoglycans are large molecules that make at tissue firmer and more resistant to compression and also act as a barrier to substances diffusing through the ECM.

Respiratory passages, nasal cavity

Pseudostratisfied columnar epithelium

A transcription factor must bind to the promoter region of a gene before the enzyme __________ _____________- is able to bind and begin transcription

RNA polymerase

Transcript is built with help of the enzyme...

RNA polymerase; binds to a gene; brings in complementary nucleotides, linking them together to form mRNA

Whats the role of reticular fibers in the ECM?

Reticular fibers are smaller fibers that interweave to form supportive networks around the cells of many tissues and also form "webs" in certain organs to trap foreign cells.

Granular organelle that makes proteins

Ribosome

Modifies and folds proteins into the correct structure

Rough Endoplasmic reticulum

Proteins destined for secretion from the cell enter the _______________ after translation, to be folded and modified.

Rough Endoplasmic reticulum

Sate of the cell cycle in which DNA is replicated

S phase

Transport of a substance across the plasma membrane against its concentration gradient using the energy from the "downhill" movement of another substance.

Secondary active transport.

Explain structure and function for Cilia

Short, motile extensions from the cell. Their structure enables them to beat rhythmically to sweep substances past the cell

Passive movement of solute across the plasma membrane

Simple diffusion

Which of the following statements about muscle tissue is false? a. smooth muscle tissue is involuntary and the cells are non striated b. cardiac muscle tissue is involuntary and the cells are striated c. skeletal muscle fibers are joined by intercalated discs d. skeletal muscle fibers are long and cylindrical striated cells.

Skeletal muscle fibers are NOT joined by intercalated discs

Detoxifies certain chemicals, makes lipids, stores calcium ions.

Smooth endoplasmic reticulum.

Why do you think the rate of cell division is different for different tissues? Where in the body would you expect to find cells that have rapid rate of division? Where might you find cells that have a slow rate of division?

Some cell types are subject to a lot of wear and tear because of the location and or function, including the cells of the skin and the gastrointestinal tract. Such cells must have a rapid rate of mitosis to replace dead or damaged cells. Cells that have slow or absent cell division include those that have complex structure and or do not have the cellular machinery for cell divisions. These cells include neurons and muscle cells.

____________ are the secretory cells of synovial membranes

Synoviocytes

Stage of mitosis in which the nuclear envelopes reassemble

Telophase

Why is regulation of the cell cyle neccessary?

The cell cycle must be tightly regulated in order to balance cell division with cell death. Improperly regulated cell division may lead to a progressive deterioration of the tissue (if cells do not divide enough) or an increase in the number of cells in a tissue (if the cells divide too often)

What are the two fluid compartments in the body, and how are they kept separate?

The cytosol (intracellular fluid) is the fluid compartment in the cells, and the extracellular fluid is the fluid outside of the cells. The two are kept separate by the cells plasma membranes.

Explain how the members of the endomembrane system interact

The smooth and rough endoplasmic reticulum completes the synthesis of lipids and proteins. They are then sent by vesicles to the golgi apparatus , which modifies and sorts the products, and then packages them into another vesicle. The vesicles are sent to lysosomes, other organelles, or the plasma membrane.

A hypothetical poison prevents transcription factors from binding to the gene for tubulin proteins. What impact would this have on mitosis, and why? What effect would the hypothetical poison have on other functions of the cell?

This poison would prevent the synthesis of tubulin proteins and therefore microtubules. This would inhibit the development of the mitotic spindle, and mitosis would be unable to proceed. Microtubules are responsible for maintaining cell shape and the positions of organelles. Without microtubules, the organelles would disperse, particularly the members of the endomembrane system. In addition, vesicles and other cell structures would not be transported from place to place, disrupting vesicular transport within the cell and between the cell and the environment. Finally if the cell has flagellum or cilia, they would be unable to function. These conditions would result in the death of a cell.

Membrane proteins often function as channels or carriers.

True

Microtubules are hollow tubes that align organelles and shuttle them to their proper places in the cell.

True

True or False Within the the nucleolus we find genes for rRNA

True

True or false: Integral membrane proteins generally span the width of the plasma membrane, whereas peripheral proteins are found on only one side of the membrane.

True

Adipose tissue functions in insulation, warmth, protections, and shock absorption, and is the major energy reserve in the body.

Truth

True or false Epithelial tissues are classified by cell shape and the number of cell layers

Truth

Transcription termination

When last triplet of gene is reached and the newly formed pre-mRNA molecule is ready for modification.

During translation at a ribosome each codon is paired with ....

a complementary tRNA (called anticodon) with its specific amino acid attached; amino acid will be added to growing peptide chain.

Mutations

a random error in gene replication that leads to a change

Lysosomes structure and function

are composed of phospholipid bilayer surrounding digestive enzymes in an acidic environment. This structure allows them to digest particles within the cell while preventing the enzymes in acid from damaging the rest of the cell.

Structure and function of Microvilli

are folds of plasma membrane that increase the surface area for absorption in cells for which absorption is a primary function.

transcription initiation

beginning of transcription, begins when protein transcription factors bind to a promoter region near gene on template strand of DNA; RNA polymerase also binds to promoter; DNA unwinds with aid of enzyme helicase

aminoacyl site (A site)

binds to incoming tRNA carrying an amino acid

Heart

cardiac muscle

Tissues are between __________ and _________ in the levels of organization.

cells; organs

Nuclear envelope structure and function

composed of a double phospholipid bilayer with large nuclear pores. It contains the chromatin and other nuclear structures within the nucleus while allowing fairly large molecules such as mRNA to move between the nucleoplasm and cytosol.

Binds, connects, supports, and transports substances throughout the body.

connective

ECM is often the primary element

connective

The ______________ membrane is composed of stratified squamous epithelium, loose connective tissue, and dense irregular connective tissue.

cutaneous

Division of the cytoplasm

cytokinesis

Ear and epiglottis

elastic cartilage

Sheets of tightly packed cells with little ECM

epithelial

Mucous membranes are composed of _____________ and the underlying loose connective tissue

epithelium

Membrane cholesterol is vital for cell to cell recognition

false! Membrane glycoproteins and glycolipids are vital for cell-to-cell recognition

Intervertebral discs, knee join

fibrocartilage

What is the role of Glycoproteins in the ECM?

hold cells in their places in a tissue and connect cells to one another and to components of the ECM.

Tight junctions make the spaces between cells _________, whereas desmosomes increase the _______ of tissue.

impermeable; mechanical strength

Transcription proceeds in 3 general stages:

initiation, elongation, termination

Which of the following is not a phase of mitosis? a. interphase b. prophase c. anaphase d. metaphase

interphase.

A hypotonic solution will cause water to move ___________ the cell and the cell will __________. A hypertonic solution will cause water to move _______ the cell and the cell will _______.

into; swell out; crenate

Mitosis

is division of a cell's nuclear material between two daughter cells.

DNA synthesis

is the replication of a cell's DNA in preparation for cell division

peptidyl site (P site)

is where amino acid is removed from its tRNA; added to growing peptide chain

Skin

keratinized stratified squamous

Gene

long chain of nucleotides; segment of DNA that determines specific sequence of amino acids in a protein.

Contains digestive enzymes

lysosomes

tRNA

made in nucleous, picks up specific amino acids and transfers them to ribosome

DNA mutations are the basis for ...

many diseases, including cancer.

Transcription

means copying the code of a gene by creating a complementary strand of mRNA

The RNA polymerase builds a strand of ___________ _______, who codons are complementary to the DNA's triplets.

messenger RNA

Osmosis

movement of a solvent from a solution with a lower solute concentration to one with a higher solute concentration

Secondary active transport

moves a substance across the plasma membrane agains its concentration gradient using the energy from another substances's concentration gradient.

Consists of excitable cells that are specialized for contraction

muscle

cells may be smooth or striated

muscle

Makes up the majority of the brain and spinal cord

nervous

Translation

occurs at ribosome where nucleotide sequence of mRNA is translated into amino acid sequence with help of transfer RNA (tRNA)

Translation

occurs in cytosol; mRNA binds with ribosome initiating synthesis of a polypeptide consisting of a specific sequence of amino acids

Anticodon

on one end of tRNA is a sequence of 3 nucleotides complementary to the codon of mRNA

Fill in the blanks: The three main components of a cell are the _________, the ______, and the __________.

plasma membrane, cytoplasm, and nucleus

Gene expression-

process by which a gene produces its product and the product carries out its function

Transcription

process of making mRNA copy of DNA (called transcript); exits nucleus through nuclear pore into cytoplasm where ribosomes are found.

Protein Synthesis

process of manufacturing proteins from DNA blueprint using RNA

Transcription

process where gene for specific protein is copied; creating messenger RNA (mRNA); exits through nuclear pore

Lymph nodes, spleen, and liver

reticular connective tissue

triplet

set of 3 nucleotides. represents a different amino acid; each amino acid may be represented by more than one triplet.

Digestive tract

simple columnar epithelium

Kidney tubules, thyroid gland

simple cuboidal epithelium

Air sacs of the lungs, squamous blood vessels

simple squamouse

Most hollow organ, eye, skin

smooth muscle

During translation, amino acids are delivered by the _______ molecule.

tRNA

Diffusion

the movement of solute molecules from a high concentration to a low concentration

Intermediate filaments structure and function

the rope like structure of intermediate filaments allows them to be flexible but very strong and therefore provide the cell with structural support.

Codon

three-nucleotide sequence on messenger RNA that codes for a single amino acid

During transcription each DNA triplet is

transcribed into a complementary RNA copy; each 3nucleotide sequence of mRNA copy is called a codon

urinary bladder

transitional epithelium

Translation means...

translating the code in the mRNA into a protein with the help of tRNA and ribosomes.

Primary active transport

transport of a substance across the plasma membrane against its concentration gradient with the use of energy from ATP

In a gene, each __________ specifies one amino acid in a protein sequence.

triplet

True or False A goblet cell is unicellular exocrine gland that secretes mucus

truth

True or false Epithelial tissues function in protection, immune defenses, secretion, transport, and sensation.

truth

Common mutagens

ultraviolet light, radiation, chemicals such as benzene, and infection with certain viruses

Membrane-enclosed structure used to transport substances through the cell

vesicle