Chapter 4: Cells

Tay Sachs

Lacks the ability to break down lipids. Fat fills up cells and they can't function. (a fatal genetic disease that causes fatty material to build up in the nerves and brain) No cure - fatal

Smooth ER

"Called this because its membranes have no ribosomes attached to their surfaces. The smooth ER has various functions in the cytoplasm, including synthesis of lipids that become part of cell membranes. In some cells, such as those of the liver, smooth ER membranes contain enzymes that convert drugs, poisons, and toxic by-products of cellular metabolism into substances that can be tolerated or more easily removed from the body." "cells that primarily synthesize lipids or break down toxic substances are packed with smooth ER but contain little rough ER."

secretory vesicles

"The modifications of the proteins within the Golgi complex include adding "zip codes" to the proteins, which tags them for sorting to their final destinations. For instance, proteins secreted from the cell are transported to the plasma membrane in secretory vesicles, which release their contents to the exterior by exocytosis. In this process, a secretory vesicle fuses with the plasma membrane and the vesicle contents are released to the outside. The contents of secretory vesicles vary, including signaling molecules such as peptide hormones and neurotransmitters, waste products or toxic substances, and enzymes (such as from cells lining the intestine). The vesicle membrane may fuse with and become part of the plasma membrane."

Rough ER

"The synthesis, processing, and trafficking (movement) of a large variety of proteins occurs on the rough ER. Those proteins represent about one third of the proteins encoded in the human genome and include enzymes, receptors, ion channels and transporters, and hormones. The proteins are synthesized on the ribosomes attached to the ER and then enter the ER lumen. Processing then occurs in which the proteins are folded into their final form, and then chemically modified (such as by the addition of carbohydrate groups to produce glycoproteins). In trafficking, the proteins are then delivered to other regions of the cell within small vesicles that pinch off from the ER, travel through the cytosol, and join with the organelle that performs the next steps in their modification and distribution. For most of the proteins made on the rough ER, the next destination is the Golgi complex, which packages and sorts them for delivery to their final destinations. The outer membrane of the nuclear envelope is closely related in structure and function to the rough ER, to which it is connected. This membrane is also a "rough" membrane, studded with ribosomes attached to the surface facing the cytoplasm. The proteins made on these ribosomes enter the space between the two nuclear envelope membranes. From there, the proteins can move into the ER and on to other cellular locations." "Cells that are highly active in making proteins to be released outside the cell, such as pancreatic cells that make digestive enzymes, are packed with rough ER but have relatively little smooth ER."

microtubules

long, hollow tubes made of the protein Tubulin (form a rigid skeleton for the cell and assist in moving substances within the cell). (gives most structure!) -Form a rigid skeleton -Provide framework for organelles/vesicles to move within a cell (uses motor proteins) "Anchor various organelles and provide tracks for vesicle movement."

Ribosomes step 2

mRNA leaves the nuclear pores and attaches to ribosomes which synthesize proteins through translation. (they put the amino acids together into polypeptides)

cyclosis/cytoplasmic streaming

movement of cytoplasm: A critical function in cells; it helps transport materials around the cells so that the cell's metabolic needs are met in an efficient way.

Microtubules (textbook)

"The wall of the microtubule consists of 13 protein filaments arranged side by side. "Functions -Moving animals cells:Animal cell movements are generated by "motor" proteins that push or pull against microtubules or microfilaments, much as our muscles produce body movements by acting on bones of the skeleton. One end of a motor protein is firmly fixed to a cell structure such as a vesicle or to a microtubule or microfilament. Using energy from ATP hydrolysis, the other end "walks" along another microtubule or microfilament by making an attachment, forcefully swiveling a short distance, and then releasing"

lysosomes

(ANIMAL CELLS MOSTLY) Vesicle that stays in the cell, containing hydrolytic (digestive) enzymes. Lysosomes break down food, waste, bacteria, and old cell parts. During protein synthesis, this happens after protein goes through the golgi apparatus and instead of secretion it stays in the cell.

Nucleus step 1

(from last unit) The DNA contains the genetic code for all proteins; the sequence of nucleotides in DNA codes for the sequence of amino acids in the proteins. DNA (genetic code) goes through TRANSCRIPTION and mRNA transcript leaves the nucleus through NUCLEAR PORES

To remain efficient cells may...

-DIVIDE into smaller cells -Make more organelles to maintain high level of efficiency inside the cell. -Some cells have specialized folds (microvilli and alveolli) Or else the cell will eventually starve to death.

6 steps of protein synthesis

1. Nucleus (DNA) 2. Ribosomes 3. (Rough) Endoplasmic Reticulum 4. Transport Vesicle 5. Golgi Apparatus 6. Secretory Vesicle

the cytoskeleton

A cellular "scaffolding" or "skeleton" contained within the cytoplasm to help keep cell shape/structure. 3 proteins make up the cytoskeleton: -microtubules (largest) -intermediate fibers (medium) -microfilaments (smallest) "The cytoskeleton also reinforces the plasma membrane and functions in movement, both of structures within the cell and of the cell as a whole. It is most highly developed in animal cells, in which it fills and supports the cytoplasm from the plasma membrane to the nuclear envelope. Although cytoskeletal structures are also present in plant cells, the fibers and tubes of the system are less prominent; much of cellular support in plants is provided by the cell wall and a large central vacuole."

Chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria a green pigment that is present in all chloroplasts. The chemical energy is used by enzymes in the stroma to make carbohydrates and other complex organic molecules from water, carbon dioxide, and other simple inorganic precursors. The organic molecules produced in chloroplasts, or from biochemical building blocks made in chloroplasts, are the ultimate food source for most organisms. The chloroplast stroma contains DNA and ribosomes that resemble those of certain photosynthetic bacteria.

Cell History

ASK

Transport Vesicle step 4

After the endoplasmic reticulum the protein is transported to the transport vesicle (a pinched off part of what the ribosomes and endoplasmic reticulum made).

Amoeba endocytosis example

Amoebas use endocytosis to engulf its food. The microfilaments push to cytoplam out of the cell membrane, allowing "pseudopods" to form around the food. Some of our white blood cells engulf bacteria this way. Lysosomes then fuse with the VESICLE and kill the bacteria inside.

lysosome

Animal A membrane enclosed organelle that contains digestive enzymes; breaks down large molecules and old cell parts that can be recycled to build new cell parts. "Small, membrane-bound vesicles that contain more than 30 enzymes for the hydrolysis (digestion) of many complex molecules, including proteins, lipids, nucleic acids, and polysaccharides. Those who deny the existence of lysosomes in plants believe that the functions of lysosomes in plants are carried out by the central vacuole. Lysosomes are formed by budding from the Golgi complex. Their hydrolytic enzymes are synthesized in the rough ER, modified in the lumen of the ER to identify them as being bound for a lysosome, moved to the Golgi complex in a vesicle, and then packaged in the budding lysosome. Lysosomal enzymes can digest several types of materials. They digest food molecules entering the cell by endocytosis when an endocytic vesicle fuses with a lysosome. In a process called autophagy, they digest organelles that are not functioning correctly."

centrioles

Animal Aids in cell division (mitosis) "Centrosome: a site near the nucleus where microtubules are formed and radiate outward; contains a paire of centrioles." "Many of the cytoskeletal microtubules in animal cells are formed and radiate outward from a site near the nucleus termed the cell center or centrosome. At its midpoint are two short, barrel-shaped structures also formed from microtubules called the centrioles"

Stem cells

As cells become tissues, they become specialized/differentiated (undifferentiated cells = stem cells). A stem cell can differentiate into many cell types (different shapes and sizes) (Ex: nerve cells, muscle cells, blood cells, epithelial cells -- cover or line surfaces and organs like the lining of blood vessels, lining of the inside of your cheeks, and skin cells)

cilia

short, hairlike projections that make "sweeping motions" (sometimes for movement).

What happens as cells get larger?

As cells get larger, the volume grows more rapidly than its SA (can tell from units); it takes longer for nutrients to be transported around. At some point, the SA gets too small to supply the large volume with raw materials-- the cell is at risk of dying! If this ratio gets too small, the cell doesn't have enough cell membrane to supply the cytoplasm with enough raw materials to survive. As cells get bigger, the SA:V ratio decreases (decreasing efficiency)

Pompe disease

Lacks enzyme to break down glycogen (animal starch - sugar) In liver and muscles (causes people to not be able to move).

Microtubules in the trachea (on test)

Cells in your trachea (breathing tube) have cilia to sweep away dust and debris from our lungs. (When debris gets into trachea, cilia move and say don't go to lungs. If you had a gene without microtubules it would lead to respiratory problems. Ex: Smokers harm the cilia and they eventually degrade and debris will get into lungs)

Why is speed of transport of materials into/out of a cell and around the inside of the cell an advantage?

Cells that can move materials (nutrients/waste) quickly can perform the life processes more efficiently! (more nutrients - more respiration - more energy = more life processes). To measure the efficiency of a cell, we calculate the cell's surface area (cell membrane) to volume (cytoplasm) ratio.

microtubules are also found in...

Centrioles Flagella and cilia (movement -- long vs short) These are structures made of microtubules, when they are in the cytoplasm, they are part of the cytoskeleton.

vacuole

Eukaryotic (plant and animal) Membrane enclosed organelle containing stored food, water, wastes; animals have many, small ones, plants have one or two large, central ones.

endoplasmic reticulum

Eukaryotic (plant and animal) A series of membrane "tubes" that allow materials to travel -Rough: With ribosomes-- synthesizes proteins to be shipped out of the cell -Smooth: Without ribosomes-- synthesizes lipids FOR MEMBRANES

golgi bodies

Eukaryotic (plant and animal) Packages, sorts, and secretes ("ships out") the products of a cell. "The Golgi complex receives proteins from the ER, then modifies and releases them. Newly synthesized proteins made in the ER that are destined to go to the Golgi complex are packaged into transport vesicles that bud off from the ER and move to the Golgi. During that transport, the proteins are modified to their final functional forms by enzymes within the cisternae. Protein modification includes the addition of carbohydrates and removing segments of the polypeptide chain.

mitochondria (organelle)

Eukaryotic (plant and animal) Performs respiration, releasing the energy from food molecules. "Mitochondria (singular, mitochondrion), located in the cells of all eukaryotic groups of organisms, are the membrane-bound organelles in which some of the reactions of cellular respiration occurs. Cellular respiration is the process by which energy-rich molecules such as sugars, fats, and other fuels are broken down to water and carbon dioxide by mitochondrial reactions, with the release of energy. Much of the energy released by the breakdown is captured in ATP. In fact, mitochondria generate most of the ATP of the cell. Mitochondria require oxygen for cellular respiration—when you breathe, you are taking in oxygen primarily for your mitochondrial reactions."

nucleus

Eukaryotic (plant and animal) Serves as the control center for cell metabolism and reproduction; contain the genetic material (DNA)

nucleolus

Eukaryotic (plant and animal) Site of the production of ribosomes; found inside the nucleus. "rRNA synthesis and ribosome assembly occurs here"

nuclear envelope

Eukaryotic (plant and animal) Controls movement inside and out of the nucleus; contains "pores"

The Endosymbiotic Theory

Explains how eukaryotes evolved from prokaryotes. 1. Small, aerobic (oxygen using) prokaryotic cells were engulfed by larger prokaryotes (a process called endocytosis - "inside the cell") 2. Rather than digesting the smaller cell, the 2 cells formed a MUTUALISTIC SYMBIOTIC (beneficial) relationship. The hose cell helped provide nutrients and the internal cell helped to produce energy. 3. Eventually, the 2 cells became interdependent (reliant on one another) to survive. CHAPTER 25

intermediate fibers

Fibrous, rope-like protein KERATIN -Stabilizes a cell's structure by resisting tension (prevents tearing of tissues) -Helps anchor nucleus and other organelles

lysosomal storage disorders

Genetic disorder (DNA mutations) that cause the lysosome to be missing an enzyme. (result from the absence of specific lysosomal enzymes thus allowing undigested material to accumulate) Ex: Tay Sachs and Pompe Disease "hydrolytic enzymes normally found in the lysosome is absent. As a result, the substrate of that enzyme accumulates in the lysosomes, and this accumulation eventually interferes with normal cellular activities."

What is the ideal SA:V ratio?

Ideally, cells should have a HIGH SA to V ratio. SMALL cells have a LARGER SA (lots of membrane) and (less cytoplasm): This allows a more efficient exchange rate with the environment.

endocytosis (textbook)

Import by endocytosis may carry proteins, larger aggregates of molecules, or even whole cells from the outside into the cytoplasm. The process, called phagocytosis (meaning "cell eating"), begins when surface receptors bind molecules on the substances to be taken in (Figure 5.14). Cytoplasmic lobes then extend, surround, and engulf the materials, forming a pit that pinches off and sinks into the cytoplasm as a large endocytic vesicle. Enzymes then digest the materials as in receptor-mediated endocytosis, and the cell permanently sequesters any remaining residues into storage vesicles or expels them by exocytosis as wastes.

chloroplasts

In endosymbiotic theory: Some of the prokaryotic cells engulfed were blue-green algal cells - which became chloroplasts. Performs photosynthesis (makes glucose). (since plants have mito and chloro they think mito was engulfed first)

mitochondria

In endosymbiotic theory: the oxygen utilizing "bacteria" became mitochondria. Performs cellular respiration (releases energy from food)

endomembrane system

Its structure includes the endoplasmic reticulum (ER) and the Golgi complex. The rough ER has ribosomes on its outer surface. Proteins synthesized by those ribosomes enter the ER lumen, where they fold into their final shape and may be modified chemically. Then they are delivered to other regions of the cell within vesicles that pinch off from the rough ER. Most of the proteins made on rough ER go to the Golgi complex. The smooth ER consists of membranes that lack ribosomes. Functions of the smooth ER include synthesis of lipids that become parts of cell membranes. The Golgi complex is a stack of flattened, membranous sacs. The cis face of this organelle receives vesicles containing proteins released from the rough ER and continues their chemical modifications. The proteins are then sorted into vesicles that pinch off from the trans face of the Golgi complex, the side that faces the plasma membrane. Some of the released vesicles remain in the cytoplasm as storage vesicles of various types, whereas others, called secretory vesicles, release their contents to the outside of the cell. In addition, some vesicles bud from the cis face of the Golgi complex to carry certain proteins that function in the ER to the ER.

What evolution occurred to prevent cells from getting too big?

Larger organisms do not have larger cells; they just have more of them. In addition to staying tiny, some cells have evolved other ways to increase their SA and therefore, their efficiency of transport. For example, some cells have membrane projections and folds. Ex: -In the small intestine: MICROFILLI (in celiac disease microfilli flatten and can;t absorb nutrients) -In the lungs: alveolli (small air sacs) for gas exchange

Cell Theory

Many scientists contributed - it took over 250 years to develop. 1. All living things are made of cells 2. Cells are the basic unit if structure and function in all organisms (can perform the life processes) 3. All cells come from other cells through the process of cell division (mitosis) (before they though life sprung from nonliving things - spontaneous generation - like mold from tiles)

Evidence of endosymbiotic theory

Mitochondria and chloroplasts are membrane bound organelles that: -are similar in size and shape to prokaryotes -each have their own set of circular DNA (like prokaryotes!) -Double membranes (showing endocytosis occurred) -Divide independently (not when the rest of the cell divides)

General Structure of Prokaryotic Cells

ONLY BACTERIA! Do not have nucleus or membrane-bound organelles. Nucleoid Region: 1 circular piece of DNA (not nucleus) Ribosomes: Synthesize Proteins Flagellum: Some bacteria have these for movement Cell Wall: Rigidity/structure/protection Cell Membrane: phospholipid bilayer (like all membranes) Cytoplasm: Not just liquid, has amino acids, nutrients, and more!

leucoplasts

Organelles that store starch (in potato cells) ONLY PLANTS

chloroplasts (organelle)

Plant Site of photosynthesis; produces sugar for plant cells. (Prokaryotic have chlorophyll but NOT chloroplasts) ON TEST "Mitochondria (singular, mitochondrion), located in the cells of all eukaryotic groups of organisms, are the membrane-bound organelles in which some of the reactions of cellular respiration occurs. Cellular respiration is the process by which energy-rich molecules such as sugars, fats, and other fuels are broken down to water and carbon dioxide by mitochondrial reactions, with the release of energy. Much of the energy released by the breakdown is captured in ATP. In fact, mitochondria generate most of the ATP of the cell. Mitochondria require oxygen for cellular respiration—when you breathe, you are taking in oxygen primarily for your mitochondrial reactions"

Mode of Nutrition (prokaryotic vs animal vs plant)

Prokaryotic (bacteria): Heterotrophic or autotrophic (cyanobacteria are photosynthetic) Animal: heterotrophic Plant: Autotrophic (performs PHOTOSYNTHESIS inside the chloroplasts)

General Shape of Cells (prokaryotic vs animal vs plant)

Prokaryotic (bacteria): Round, rod, or spiral (10x - 100x smaller than eukaryotic cells) Animal: Irregular, round (many specialized cells may have very specific shapes) Plant: Boxy, rectangular (Keeps its shape by the CELL WALL made of CELLULOSE or fiber)

Cell membrane

Prokaryotic and Eukaryotic Controls the movement into and out of the cell; made of phospholipids "The plasma membrane itself performs several vital functions in prokaryotes. Besides transporting materials into and out of the cells, it contains most of the molecular systems that metabolize food molecules into the chemical energy of ATP. In photosynthetic prokaryotes, the molecules that absorb light energy and convert it to the chemical energy of ATP are also associated with the plasma membrane or with internal, saclike membranes derived from the plasma membrane."

ribosomes

Prokaryotic and Eukaryotic Smallest organelles (no membranes) which are the site of protein synthesis "Small, roughly spherical particles in the cytoplasm, the ribosomes, use the information in the mRNA to assemble amino acids into proteins." "Both: free is cytosol which synthesizes proteins that usually remain in cell OR attached to rough ER for synthesis of proteins but follow specific path to other organelles within the cell.)

DNA/chromosomes

Prokaryotic and Eukaryotic The genetic material; in eukaryotes it's linear, in prokaryotes its circular

cytoplasm

Prokaryotic and Eukaryotic Watery material/ gel which contains many of the materials (nutrients and ions) involved in metabolism (aka cytosol)

cell wall

Prokaryotic and plant Gives cells its shape/structure and provides protection (outside the cell membrane); in plants it contains cellulose, in bacteria it contains peptidoglycan.

exocytosis

SECRETION: 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.

(Rough) Endoplasmic Reticulum step 3

The Rough Endoplasmic Reticulum transports and modifies the protein. -The ribosomes attach to it and allows them to make proteins and travel. As it travels through the protein gets modified.

exocytosis (textbook)

The export of materials by exocytosis primarily carries secretory proteins and some waste materials from the cytoplasm to the cell exterior. In exocytosis, secretory vesicles originated by budding from the Golgi complex move through the cytoplasm along microtubules of the cytoskeleton and contact the plasma membrane. In one major mechanism of exocytosis, the vesicle membrane fuses with the plasma membrane, releasing the contents of the vesicle to the cell exterior. or example, in animals, glandular cells secrete peptide hormones or milk proteins, and cells that line the digestive tract secrete mucus and digestive enzymes. Plant cells, fungal cells, and bacterial cells use exocytosis to secrete proteins and other macromolecules associated with the cell wall, including enzymes, proteins, and carbohydrates. Fungi and bacteria also secrete enzymes by exocytosis to digest nutrients in their environments. Finally, all organisms use exocytosis to place integral membrane proteins in the plasma membrane. 3D Anim

Golgi Apparatus step 5

The golgi apparatus receives the incoming protein (from transport vesicle) then packages, sorts, and prepares the protein for secretion. (close to cell membrane bc that is where things get shipped off)

Secretory Vesicle step 6

The secretory vesicle fuses with the cell membrane, releasing the protein outside the cell. Types of proteins secreted: enzymes and hormones (most common). (get into bloodstream and body)

What is a cell?

The smallest unit of STRUCTURE and FUNCTION in all living things. (Must be able to carry out all the life processes through organelles -- nutrition, synthesis, transport, growth, reproduction, respiration, regulation, excretion -- all required to maintain homeostasis.) Every cell is enclosed in a membrane to maintain an internal environment separate from the external environment. NOW COMPARISON B/W PRO AND EUK (IN NOTES)

microfilaments

Thin, threadlike strands of contractile protein, ACTIN. -Microfilaments aid in moving the cytoplasm around the cell: CYCLOSIS or CYTOPLAM STREAMING (contract - relax - contract - relax). (when cell moves, whole thing shifts, the proteins tighten and relax allowing cytoplasm to move) " Microfilaments are involved in the actively flowing motion of cytoplasm called cytoplasmic streaming, which can transport nutrients, proteins, and organelles in both animal and plant cells, and which is responsible for amoeboid movement. When animal cells divide, microfilaments are responsible for dividing the cytoplasm " CHAPTER 43

On test, how will you explain that one cell is more efficient than another?

_____ has a larger SA to V ratio. Therefore, it has more cell membrane contact with the environment (best exchange rate_ which means it will best meet the metabolic needs.