Unit 1 - Chapter 2 Cells The Living Units

The cell life cycle encompasses what?

interphase, in which the cell grows and carries on its usual activities; and cell division, or the mitotic phase, during which it divides into two cells. Cytokinesis

The Cell Life Cycle

interphase, mitosis, cytokinesis

Smooth muscle

involuntary muscle found in internal organs

Cytoplasmic Organelles

little organs

Sperm

male gamete

What is mitosis, and what are the phases?

mitosis, or division of the nucleus, and cytokinesis, or division of the entire cell into two cells

Fluid Mosaic Model

model that describes the arrangement and movement of the molecules that make up a cell membrane

Nucleoside

nitrogenous base + sugar

Centromeres

Located in the center of the "X", they hold the chromatids together in a chromosome. They also help the chromosomes attach to the spindle fibers.

Lysosomes

Lysosomes are found in all animal cells, but are most numerous in disease-fighting cells, such as white blood cells. This is because white blood cells must digest more material than most other types of cells in their quest to battle bacteria, viruses, and other foreign intruders.

Lysosomes

Lysosomes are the janitorial crew and recycling center; they break down used proteins and other cellular debris. (Phagocytosis)

Chart the cells that fight disease. Detail the name and function of each. Include similarities and differences.

Macrophage (a phagocytic cell). This cell extends long pseudopods to crawl through tissue to reach infection sites. The many lysosomes within the cell digest the infectious microorganisms it takes up.

Centrosomes

Microtubule-organizing centers that help to form and organize the mitotic spindle during mitosis

What are the main cellular process in which the centrosome is involved?

Microtubules - largest of the cytoskeletal proteins; hollow tubules made of tubulin subunits; originate from the centrosome; allow for movement of organelles with the use of motor proteins, kinesins, and dyneins

Mitochondria

Mitochondria are the power plant; they make energy.

How are diffusion and osmosis the same and different?

Molecules through the plasma membrane - both, osmosis H2O only

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

What cells would have a large number of mitochondria? Why?

Muscle cells and heart cells

Cardiac muscle

Muscle of the heart

Detail the name and function of each.

Nerve cell (neuron). This cell has long processes for receiving messages and transmitting them to other structures in the body.

Compare and contrast active transport and facilitated diffusion.

Such substances can cross the plasma membrane only by means of specific transport mechanisms that use the integral proteins to carry or pump molecules across the membrane or to form channels through which specific molecules pass. Some of these molecules move down their concentration gradient, diffusing through the plasma membrane by moving through a specific integral protein. This transport process is called facilitated diffusion. Other integral proteins move molecules across the plasma membrane against their concentration gradient, a process called active transport, which requires the use of energy

Guanine

The base that pairs with Cytosine in DNA

Cytosine

The base that pairs with Guanine with DNA

Adenine

The base that pairs with Thymine in DNA

Organelles

The cell's functions are carried out by the cell's many subunits called organelles

Centrosome matrix

The centrosome is a spherical structure in the cytoplasm near the nucleus. It contains no membranes. Instead, it consists of an outer cloud of protein called the centrosome matrix and an inner pair of centrioles

Prometaphase

The second stage of mitosis, in which discrete chromosomes consisting of identical sister chromatids appear, the nuclear envelope fragments, and the spindle microtubules attach to the kinetochores of the chromosomes.

What is cytokinesis? Why is it important?

The separation of one cell into two at the end of the cell cycle is called cytokinesis, literally "cells moving (apart)

Cytosol

The soluble portion of the cytoplasm, which includes molecules and small particles, such as ribosomes, but not the organelles covered with membranes.

Fibroblast

a cell in connective tissue which produces collagen and other fibers.

Thymine

a compound which is one of the four constituent bases of nucleic acids. A pyrimidine derivative, it is paired with adenine in double-stranded DNA.

Erythrocyte

a mature red blood cell

Plasma membrane

a microscopic membrane of lipids and proteins that forms the external boundary of the cytoplasm of a cell or encloses a vacuole, and that regulates the passage of molecules in and out of the cytoplasm.

Exocytosis

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

Selectively permeable

a property of cell membranes that allows some substances to pass through, while others cannot

Neuron

a specialized cell transmitting nerve impulses; a nerve cell.

Phospholipid bilayer

a two-layered arrangement of phosphate and lipid molecules that form a cell membrane, the hydrophobic lipid ends facing inward and the hydrophilic phosphate ends facing outward.

ATP, ADP

adenosine triphosphate (atp) Molecule in cells that stores and releases chemical energy for use in body cells.

Mitochondrial theory

aging caused by decay of mitochondria; oxidative damage

Chromatid

one half of a duplicated chromosome

Endoplasmic reticulum

part of the production division; rough ER produces proteins, and smooth ER metabolizes lipids and stores calcium.

Receptors

parts of the cell membrane that receive the neurotransmitter and initiate or prevent a new electric signal

Integral proteins

penetrate the hydrophobic interior of the lipid bilayer

Why is there so much cellular diversity in the body?

permits organization of cells into more complex tissues and organs

Phagocytosis

process in which extensions of cytoplasm surround and engulf large particles and take them into the cell

Include all of the sub-phases.

prophase, prometaphase, metaphase, anaphase, telophase

Histone

protein molecule around which DNA is tightly coiled in chromatin

Enzyme

protein that acts as a biological catalyst

Cis/trans- face

receiving and shipping departments of the golgi apparatus

Rough ER

rough ER produces proteins

Robert Hooke

scientist Robert Hooke first observed plant cells with a crude microscope in the late 1600s

Epithelial cell

skin cells that cover the external body surface and line the internal surfaces of organs

Smooth ER

smooth ER metabolizes lipids and stores calcium

Lipid droplets

spherical drops of stored fat. They can have the same size and appearance as lysosomes but can be distinguished by their lack of a surrounding membrane. Only a few cell types contain lipid droplets: Small lipid droplets are found in liver cells, large ones in fat cells.

Sister chromatid

structure that contains identical DNA copies and is formed during DNA replication

Transcription

(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA

Detail the main events of each phase and sub-phase.

-grows (G1) -cell replicates (S) -cell prepares for division (G2) -cell division (M) (M) prophase, prometaphase, metaphase, anaphase, telophase

Compare and contrast the three main theories related to cellular aging.

1. mitochondrial theory of aging -decrease in energy production by free-radical-damaged mitochondria weakens and ages the cells 2. Genetic theories of aging propose that aging is programmed into our genes. Telomeres—"end caps" on chromosomes: limit the number of times that a cell can divide Telomerase—prevents telomeres from degrading; adds to the 3' end of the DNA to prevent genetic loss 3. Free radical theory Damage from by-products of cellular metabolism Radicals build up and damage essential molecules of cells

Nucleotide

A building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Free radical theory

A microbiological theory of aging stating that people age because when their cells metabolize energy, they generate waste that includes unstable oxygen molecules, known as free radicals, that damage DNA and other structures.

Skeletal muscle

A muscle that is attached to the bones of the skeleton and provides the force that moves the bones.

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction.

Endocytosis

A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane.

RNA

A single-stranded nucleic acid that passes along genetic messages

Chromosome

A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins. Chromosome - fully compacted structure ready for Metaphase. There are 23 pairs (46 chromosomes) of chromosomes found in the somatic cells of human body, of which the 22 pairs are represented by the autosomes (chromosomes which do not participate in sex determination) while one pair is represented by the sex chromosomes.

Ion

An atom or group of atoms that has a positive or negative charge.

What cells would have a large number of ribosomes? Why?

Stomach cells have lots of golgi apparatus and therefor a lot of ribosomes.

Chart the cell(s) that store nutrients.

Fat cells Lipid droplets stored in cytoplasm

Cisternae

Flattened, membrane-bound compartments that make up the Golgi apparatus.

Why is the plasma membrane considered a mosaic?

Fluid Mosaic Model - the phospholipid molecules of the lipid bilayer move fluidly laterally; interspersed through the membrane are various protein molecules

Nucleolus

Found inside the nucleus and produces ribosomes

Macrophage

Found within the lymph nodes, they are phagocytes that destroy bacteria, cancer cells, and other foreign matter in the lymphatic stream.

Cilia

Functionally, centrioles act in forming cilia and flagella (p. 76 in Chapter 4) and the mitotic spindle. Cilia and flagella move liquid past the surface of the cell. For single cells, such as sperm, this enables them to swim. For cells anchored in a tissue, like the epithelial cells lining our air passages, this moves liquid over the surface of the cell (e.g., driving particle-laden mucus toward the throat).

What are the three phases of Interphase?

G1, S, G2

Glycosomes

Glycosomes ("sugar-containing bodies") store sugar in the form of glycogen, which is a long branching chain of glucose molecules, the cell's main energy source. Glycosomes also contain enzymes that make and degrade the glycogen into its glucose subunits. Structurally, glycosomes are dense, spherical granules. They resemble ribosomes, but their diameter is twice as large.

What cell types would have an increased amount of glycosomes? Why?

Glycosomes store sugar in the form of glycogen, which is a long branching chain of glucose molecules, the cell's main energy source.

Golgi apparatus

Golgi apparatus is the packaging and shipping division; it packages proteins for use either within or outside of the cell. (Like UPS)

Matthias Schleiden and Theodor Schwann

However, it was not until the 1830s that two scientists, Matthias Schleiden and Theodor Schwann, boldly asserted that all living things are composed of cells.

What are the three main components of cells and why is each important?

Human cells have three main parts: the plasma membrane, the cytoplasm, and the nucleus

What type of molecules does the mitochondria break-down?

Hydrogen off of glucose to make acid environment, then makes ATP

Cell Theory

In biology, cell theory is the historic scientific theory, now universally accepted, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells.

Why are these cytoplasmic inclusions included in the list of cytoplasmic organelles?

Inclusions are temporary structures in the cytoplasm that may or may not be present in a given cell type. Inclusions include pigments, crystals of protein, and food stores. The food stores, by far the most important kind, are lipid droplets and glycosomes.

The Cytoplasm

Internal to the plasma membrane is the cytoplasm (si'to-plazm), which makes up the bulk of the cell, contains most of the cellular organelles, and surrounds the nucleus.

What is the cytoplasm?

Internal to the plasma membrane is the cytoplasm, which makes up the bulk of the cell, contains most of the cellular organelles, and surrounds the nucleus.

What type of cell would have an increased amount of lipid droplets? Why?

Liver - Only a few cell types contain lipid droplets: Small lipid droplets are found in liver cells, large ones in fat cells.

The Nucleus

The nucleus (nu'kle-us) controls cellular activities and lies near the cell's center. The nucleus is the chief executive officer (CEO); it directs the operation of the cell.

How does the structure of the mitochondria affect its function?

The outer membrane covers the organelle and contains it like a skin. The inner membrane folds over many times and creates layered structures called cristae. The fluid contained in the mitochondria is called the matrix. The folding of the inner membrane increases the surface area inside the organelle.

The Plasma Membrane

The plasma membrane is the boundary fence and security gate; it forms the boundary of the cell and selectively allows materials to pass into and out of the cell.

What is the plasma membrane?

The plasma membrane is the outer boundary of the cell. It is composed of lipids (phospholipids), sugars (glycolipids and glycoproteins), and proteins.

cytoskeleton and other cellular elements.

"Cell skeleton" - network of proteins that support the cell, help maintain shape, allow for movements Three types of proteins Microfilaments - thinnest protein filament Actin and myosin interact with each other to produce movement within the cell; unstable, break and reform Intermediate Filaments - stable, tough, insoluble protein fibers; resist pulling forces; link cells together Microtubules - largest of the cytoskeletal proteins; hollow tubules made of tubulin subunits; originate from the centrosome; allow for movement of organelles with the use of motor proteins, kinesins, and dyneins

What molecules are produced by the mitochondria?

ATP

Centrioles

Barrel-shaped organelle formed of microtubules and located near the nucleus of the cell; active in cell division.

Nucleosome

Bead-like structure in eukaryotic chromatin, composed of a short length of DNA wrapped around a core of histone proteins

Chart the cells that move organs and body parts.

Cardiac muscle, Skeletal muscle and smooth muscle cells

Pinocytosis

Cell drinking A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.

Interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

G1

Cell growth and normal functions

What are cells?

Cells are the smallest living units in the body. Each cell performs all the functions necessary to sustain life.

Why is the plasma membrane described as fluid?

Cellular boundary; semipermeable barrier Phospholipids arrange in a bilayer Fluid Mosaic Model - the phospholipid molecules of the lipid bilayer move fluidly laterally; interspersed through the membrane are various protein molecules Integral proteins - firmly embedded in or attached to the bilayer Transmembrane proteins - integral proteins that span the entire length of the membrane Peripheral proteins - loosely attached to the membrane surface; allow for cell to cell communication and connectivity; help maintain the integrity of the membrane Glycocalyx - carbohydrate molecules attached to peripheral and integral proteins; helps bind cells together; unique to each type of cell

Name the components of the Centrosomes and function of each

Centrosome - non-membrane bound structure; consists of a centrosome matrix and a pair of centrioles Centrosome Matrix - amorphous region of protein where microtubules grow and elongate Centrioles - made of 9 sets of microtubule triplets; stable structure; form cilia and flagella

Describe Chargaff's Rules and why these rules are important to the genetic code.

Chargaff's rules state that DNA from any cell of any organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine should be equal to cytosine and the amount of adenine should be equal to thymine. This pattern is found in both strands of the DNA. They were discovered by Austrian born chemist Erwin Chargaff, in the late 1940s.

What do the "checkpoints" ensure, and why is it important to have these "checkpoints"?

Checkpoints that evaluate cellular activities such as cell growth, DNA replication, and mitotic spindle formation occur throughout the cell cycle. The G1 checkpoint assesses cell size before DNA synthesis, and the G2/M checkpoint checks for DNA damage and accuracy of replication. Mitosis can be halted at these checkpoints, thus preventing damaged cells from dividing. Mutation in genes at these checkpoints can cause uncontrolled cell division and lead to tumor growth.

Metaphase

Chromosomes line up in the middle of the cell

In what type of cells would peroxisomes be most prevalent?

Contain oxidase enzymes that detoxify alcohol, hydrogen peroxide, and other harmful chemicals. Liver, kidneys, brain, lungs

Detail the name and function of each.

Contractile filaments allow cells to shorten forcefully

Ribosome

Cytoplasmic organelles at which proteins are synthesized.

What is the cytoskeleton and why is important to the cell?

Cytoskeletal elements form the framework and infrastructure of the building; they maintain cell shape and structure and transport materials within the cell.

Telomeres

DNA at the tips of chromosomes

What are nucleosomes and why are they necessary?

DNA coiled around histones. Nucleosomes are thought to carry epigenetically inherited information in the form of covalent modifications of their core histones.

How is the structure of DNA directly related to its function?

DNA is a double helix constructed of chains of nucleotide molecules. Each nucleotide consists of a sugar, phosphate, and one of four bases: thymine (T), adenine (A), cytosine (C), or guanine (G).

Why do various types of cells have varying abundance of organelles?

Different types of cells have different amounts of some organelles. For instance, cells that use a lot of energy tend to contain large numbers of mitochondria. That's why very active muscle cells are often full of mitochondria.

Osmosis

Diffusion of water through a selectively permeable membrane

Nuclear envelope

Double membrane perforated with pores that control the flow of materials in and out of the nucleus.

Why are cells important?

Each cell can: Obtain nutrients and other essential substances from the surrounding body fluids. Use these nutrients to make the molecules it needs to survive. Dispose of its wastes. Maintain its shape and integrity. Replicate itself.

Active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

Detail the name and function of each.

Epithelial cell Pack together in sheets Intermediate fibers resist tearing during rubbing or pulling Fibroblast Secretes cable-like fibers Erythrocyte (red blood cell) Carries oxygen in the bloodstream

Chart the cells that connect body parts or cover organs.

Epithelial cells - Cells that cover and line body organs

How does this diversity contribute to the overall function of the human body?

Ex: muscle cells contract, allowing movement. Nerve cells generate and conduct electrical impulses, allowing communication between the central nervous system (brain and spinal cord) and the rest of the body.

How are extended and condensed chromatin different functionally?

Extended Chromatin - two turns of the double helix wrap around histone proteins to create a nucleosomes; active region Condensed Chromatin - 30nm fiber; coiling of the nucleosomes to form a tight helical fiber; inactive

Chart the cell(s) that gather information.Detail the name and function of each. Include similarities and differences.

Nerve cell (neuron). This cell has long processes for receiving messages and transmitting them to other structures in the body. The processes are covered with an extensive plasma membrane, whose components are continually recycled; a large rough ER is present to synthesize membrane components.

Is the nucleus considered an organelle? Why or why not?

Nucleoli are not typical organelles for the reason that they have no lipid membrane, making it with of the few non-membrane bound organelles in the cell.

What is the importance of peroxisomes in the cell?

Only in certain cells. Waste removal system. Contain a number of enzymes Oxidases - use oxygen to neutralize by-products of metabolism; produces hydrogen peroxide Catalases -converts hydrogen peroxide into oxygen

Detail the name and function of each.

Oocyte (female) Largest cell in the body Divides to become an embryo upon fertilization Sperm (male) Built for swimming to the egg for fertilization Flagellum acts as a motile whip

Chart the cells of reproduction

Oocyte (female) Sperm (male)

Include similarities and differences.

Oocyte - Largest cell in the body Divides to become an embryo upon fertilization Sperm (male) small Built for swimming to the egg for fertilization Flagellum acts as a motile whip

Golgi apparatus function

Packages labels ships through three pathways Stack of polar flattened sacs; cis- and trans-faces Cis-face receives transport vesicles Vesicles bud off of the trans-face Sorts, processes, and packages products of the RER Three pathways: Protein product contained in secretory vesicles excreted by exocytosis; occurs in glandular cells Membrane of vesicle fuses with membrane; occurs in all cells Vesicle becomes a lysosome or peroxisome that continues to exist independently in the cytoplasm

Coated pit

Parts of the cell membrane that have a hairlike coating necessary for endocytic functions. These portions of the cell membrane pinch off to form vesicles that aid in the intracellular transport of materials.

What are organelles?

Perform functions necessary to sustain life

Peroxisomes

Peroxisomes are the toxic waste treatment facility; they neutralize and remove toxic substances within the cell.

What are the three types of endocytosis and why is each uniquely important to the cell?

Phagocytosis ("cellular eating") Pinocytosis ("cellular drinking") Receptor-mediated endocytosis

endocytosis.

Phagocytosis - "cell eating" - utilized by white blood cells Pinocytosis - "cell drinking" - utilized by the cells of the intestinal lining Receptor-mediated - molecules that act as chemical messengers (hormones, enzymes, LDLs) attach to a specific protein (receptor) in the cell membrane, Receptor-mediated endocytosis is a major activity of the plasma membranes of eukaryotic cells. More than 20 different receptors have been shown to be selectively internalized by this pathway

Anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

What is the main function of the mitochondria?

Produces energy for cellular function Release energy from chemical bonds Transfer energy to ATP Dual membrane Smooth outer membrane Cristae - inner membrane folds; location of the electron transport chain Matrix - inner jelly-like substance; location of Citric Acid Cycle

Peripheral proteins

Protein appendages loosely bound to the surface of the membrane and not embedded in the lipid bilayer.

What is the main function of the ribosomes?

Protein producers Contains: Protein (catalytic) rRNA Free floating or membrane bound

transcription, translation, and replication

Replication - nucleus - DNA Transcription -extended chromatin where DNA's genetic code is copied onto messenger RNA molecules. Translation - ribosomes

Protein

Ribosomes and rough ER produce proteins; the Golgi apparatus packages proteins.

Compare and contrast the two types of endoplasmic reticulum with regard to structure, function, etc.

Rough ER - membrane enclosed cisterns; detachable ribosomes stud the external membrane, releasing proteins into the interior for processing and export; makes digestive and metabolic enzymes. Integral proteins and phospholipids - stomach Smooth ER - continuous with the Rough ER; metabolizes lipids; important in detoxifying the cell; store calcium specifically in muscle cells LIVER

What type of cells would have a larger amount of smooth ER? Rough ER? Why?

Rough ER - pancreatic cells, stomach Smooth ER - muscle cells, liver cells

Rudolf Virchow

Shortly thereafter, the pathologist Rudolf Virchow extended this idea by contending that cells arise only from other cells. Virchow's thesis was revolutionary because it challenged the prevailing theory of spontaneous generation, which held that organisms can arise from nonliving matter.

Vesicle

Small membrane-bound sac that functions in moving products into, out of, and within a cell.

Coated vesicle

Small membrane-enclosed sac that wears a distinctive layer of proteins on its cytosolic surface. It is formed by pinching-off of a protein-coated region of cell membrane.

Membrane Transport

Small, uncharged molecules, such as oxygen, carbon dioxide, and fat-soluble molecules, can pass freely through the lipid bilayer of the plasma membrane through a process called simple diffusion. Diffusion is the tendency of molecules in a solution to move down their concentration gradient; that is, the molecules move from a region where they are more concentrated to a region where they are less concentrated. Water, like other molecules, diffuses down its concentration gradient. The diffusion of water molecules across a membrane is called osmosis

Why is it important to note that the Golgi has two "faces"? How does this relate to the function?

Stack of polar flattened sacs; cis- and trans-faces Cis-face receives transport vesicles Vesicles bud off of the trans-face

Describe the Endosymbiont Theory and why this is the theory for mitochondria.

The endosymbiotic theory deals with the origins of mitochondria and chloroplasts, two eukaryotic organelles that have bacteria characteristics. Mitochondria and chloroplasts are believed to have developed from symbiotic bacteria, specifically alpha-proteobacteria and cyanobacteria, respectively.

Describe in detail the fluid mosaic model.

The fluid mosaic model of membrane structure depicts the plasma membrane as a double layer, or bilayer, of lipid molecules with protein molecules embedded within it. The most abundant lipids in the plasma membrane are phospholipids. Like a lollipop on two sticks, each phospholipid molecule has a polar "head" that is charged, and an uncharged, nonpolar "tail" made of two chains of fatty acids. The polar heads are attracted to water—the main constituent of both the cytoplasm and the fluid external to the cell—so they lie along the inner as well as the outer face of the membrane. The nonpolar tails avoid water and line up in the center of the membrane. The result is two parallel sheets of phospholipid molecules lying tail to tail, forming the membrane's basic bilayered structure.

Glycocalyx

The glycocalyx is a carbohydrate-enriched coating that covers the outside of many eukaryotic cells and prokaryotic cells, particularly bacteria . When on eukaryotic cells the glycocalyx can be a factor used for the recognition of the cell. On bacterial cells, the glycocalyx provides a protective coat from host factors.

Compare and contrast the two main membrane proteins.

The membrane proteins are of two distinct types: integral and peripheral. Integral proteins are firmly embedded in or strongly attached to the lipid bilayer. Some integral proteins protrude from one side of the membrane only, but most are transmembrane proteins that span the whole width of the membrane and protrude from both sides (trans = across). Peripheral proteins, by contrast, are not embedded in the lipid bilayer at all. Instead, they attach rather loosely to the membrane surface. The peripheral proteins include a network of filaments that helps support the membrane from its cytoplasmic side. Without this strong, supportive base, the plasma membrane would tear apart easily.

In what ways does the function of the cell affect the cell?

The structure depends on what function it will perform. RBCs -small, flat discs, fit through narrow capillaries, around corners in the circulatory system to deliver O2. Neurons carry messages from the brain and spinal cord to the rest of the body, using electrical signals - Since electrical signals travel much faster than chemical signals, neurons are long and thin. The elongated shape of muscle cells allows the contraction proteins to line up in an overlapping pattern that makes muscle flexing possible. And human sperm cells' structures allow them to "swim" long distances to reach an egg for fertilization, flagella, very small, carrying little more than the DNA for a potential zygote.

S phase

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.

What are the tenets of the Cell Theory?

The three tenets to the cell theory are: All living organisms are composed of one or more cells. The cell is the basic unit of structure and organization in organisms. Cells arise from pre-existing cells.

How are endocytosis and exocytosis the same and different?

The transport of large particles and molecules through the membrane. Also known as vesicular transport Endocytosis - the mechanism by which large molecules ENTER the cell Exocytosis - the mechanism by which large molecules EXIT the cell

Receptor-mediated endocytosis

The uptake of specific molecules based on a cell's receptor proteins

What is a chromosome and how many are in the human body?

There are 46 chromosomes (23 pairs) in a human body cell with the exception of the sex cells. One of each pair is inherited from the mother's egg, the other from the father's sperm.

Plasma membrane defines the extent of the cell

This thin, flexible layer defines the extent of the cell, thereby separating two of the body's major fluid compartments: the intracellular fluid within the cells and the extracellular fluid that lies outside and between cells.

What is the primary function of the plasma membrane?

This thin, flexible layer defines the extent of the cell, thereby separating two of the body's major fluid compartments: the intracellular fluid within the cells and the extracellular fluid that lies outside and between cells.

What are the main functions of the nucleus?

To house and copy DNA and pass it on to daughter cells in cell division; to build ribosomal subunits; to transcribe DNA instructions into RNA and thereby control the cell's functions.

Are ribosomes "technically" organelles? Why or why not?

Unlike most organelles, they are not surrounded by a membrane, but are constructed of proteins plus ribosomal RNA (RNA = ribonucleic acid). Each ribosome consists of two subunits that fit together like the body and cap of an acorn.

Telomerase

catalyzes the lengthening of telomeres in germ cells

G2

cell prepares to divide, grows and synthesizes proteins

Fat cell

cell that stores nutrients

Condensed chromatin

contains tightly coiled strands of DNA - wrap around histones

Extended chromatin

contains uncoiled strands of DNA. Under the microscope in its extended form, chromatin looks like beads on a string. The beads are called nucleosomes. Each nucleosome is composed of DNA wrapped around eight proteins called histones.

What are the functions of cells?

covering, lining, storage, movement, connection, defense, communication, reproduction

Where are the ribosomes located?

cytoplasm and rough ER

Translation

decoding of a mRNA message into a polypeptide chain

DNA

deoxyribonucleic acid, a self-replicating material present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

phagolysosome

digestive vesicle formed by the fusing of a lysosome with a phagosome

Karyokinesis

division of a cell nucleus during mitosis.

Cytokinesis

division of the cytoplasm to form two separate daughter cells

Mitosis

division of the nucleus

What would happen to the membrane if it was made of lipids only, instead of phospholipids? How would this affect functionality of the membrane and of the cell as a whole?

each phospholipid molecule has a polar "head" that is charged, and an uncharged, nonpolar "tail" made of two chains of fatty acids. The polar heads are attracted to water—the main constituent of both the cytoplasm and the fluid external to the cell—so they lie along the inner as well as the outer face of the membrane. The nonpolar tails avoid water and line up in the center of the membrane. The result is two parallel sheets of phospholipid molecules lying tail to tail, forming the membrane's basic bilayered structure. Sugar groups are attached to about 10% of the outer lipid molecules, making them "sugar-fats," or glycolipids (gli″ko-lip′ids). The plasma membrane also contains substantial amounts of cholesterol, another lipid. Cholesterol makes the membrane more rigid and increases its impermeability to water and water-soluble molecules.

Genetic theory

emphasizes the role of genes in the development of age-related changes

Ovum

female gamete

Prophase

first and longest phase of mitosis in which the genetic material inside the nucleus condenses and the chromosomes become visible

Cytoplasmic inclusions

temporary structures in the cytoplasm that may or may not be present in a given cell type. Inclusions include pigments, crystals of protein, and food stores. The food stores, by far the most important kind, are lipid droplets and glycosomes.

Aging

the combination of biological, psychological, and social processes that affect people as they grow older

Telophase

the final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

Cytoplasm

the material or protoplasm within a living cell (except the nucleus)

Facilitated diffusion

the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins

Cellular Diversity

the trillions of cells in the human body are made up of 200 different cell types that vary greatly in size, shape and function

Include similarities and differences.

voluntary and involuntary - heart, bladder involuntary, muscles voluntary