Bio Chapter 3

organelles

"little organs" that carry out specialized functions, such as digesting nutrients or packaging cellular products

cell doctrine

1. all living things are composed of cells and cell products 2. a single cell is the smallest unit that exhibits all the characteristics of life 3. all cells come only from preexisting cells

types of passive transport

1. diffusion through the lipid bilayer 2. diffusion through channels (proteins) 3. facilitated transport

stem cells

a cell from which other types of more specialized cells originate. the ultimate stem cell is the fertilized egg, as well as the first eight cells of a human embryo.

nucleolus

a dense region within the nucleus where the component of ribosomes are synthesized. the components pass through the nuclear pores to be assembled into ribosomes in the cytoplasm

concentration gradient

a difference in concentrations between regions of a solution

passive transport

a method of transporting a molecule through a cell membrane without requiring the cell to expend any energy. this relies on the mechanism of diffusion

coenzyme

a small molecule that assists an enzyme by transporting small molecular groups.

peroxisomes

a vesicle that contains an enzyme so powerful that it needs to be kept within a membrane to avoid damaging the rest of the cell. it destroys various toxic wastes produced inside the cell, including hydrogen peroxide. they also destroy compounds that have entered the cell from the outside, such as alcohol

citric acid cycle

also called Krebs cycle, is a series of 8 sequential steps in which each acetyl group is completely disassembled to CO2 waste and various high-energy products. it produces two ATP, six NADH and two FADH2, which carry high-energy hydrogen ions and electrons to the electron transport system

sodium-potassium pump

an active transport protein in the cell membrane that uses energy from breaking down ATP to transport sodium out of the cell and potassium into the cell.

characteristics of a cell

despite structural differences, all cells are small in one or more dimensions, requiring considerable magnification to be seen (they can't be seen by the human eye). the total metabolic activities of a cell are proportional to its volume of cytoplasm (cell size). to support its activities, every cell needs raw materials in proportion to its size and every cell needs a way to get rid of waste. All raw materials, energy, and waste can enter or leave the cell only by crossing the plasma membrane. the smaller the cell, the more effectively it can obtain raw materials and get rid of wastes.

isotonic

extracellular fluid is isotonic if it has the same solute concentration as the intracellular solutions

explain the metabolic pathways for fats, glycogen, and proteins

fats can be broken down into fatty acids -> acetyl CoA and glycerol -> pyruvate -> preparatory step glycogen is broken down into glucose through glycolisis protein is broken down into amino acids -> carbon backbone-> pyruvate and NH3 -> urea (waste)

cellular respiration

glycolysis - preparatory step - the citric acid cycle - electron transport system. 36 ATP are produced

cilia and flagella

hairlike cilia and whiplike flagella extend from the surface of the cell and are specialized to help with movement. they are composed primarily of protein microtubules held together by connecting elements and surrounded by a plasma membrane. in humans, flagella are only found on sperm cells and they allow the entire cell to move from one place to another. cilia move materials along the surface of a cell with a brushing motion and are common on surfaces of cells that line the airways and in certain ducts within the body.

eukaryotes

human cells, nearly every type has three basic structural components 1. a plasma membrane 2. a nucleus - the core that houses the cell's genetic material and functions as its "information center" 3. cytoplasm - "cell material" that includes everything inside the cell except the nucleus. it's composed of cytosol and organelles that carry out specialized functions

endoplasmic reticulum

in conjunction with its attached ribosomes, synthesizes most of the chemical compounds made by the cell.

anaerobic metabolism

in the absence of oxygen, glycolysis is the only ATP producing step available. Glycolysis without oxygen results in lactic acid build up

plasma membrane

it is constructed of two layers of phospholipids, called a lipid bilayer, in addition to cholesterol and various proteins. all cells are surrounded by this outer membrane. it encloses the material inside the cell, which is mostly water but also contains ions, enzymes, and other structures the cell requires.

catabolism

larger molecules are broken down, a process that releases energy. ex. the breakdown of glucose into water, carbon dioxide, and energy.

prokaryotes

like bacteria, they have a plasma membrane that is surrounded by a rigid cell wall, but they lack a nucleus and organelles. their genetic material is concentrated in a particular region, but it is not specifically enclosed within a membrane-bound nucleus. they also lack most of the organelles found in eukaryotes.

secretory vesicle

membrane-bound shipping container that contains products for export from the cell. most secretory products are made in the golgi apparatus so secretory vesicles generally derive from the golgi membrane

explain what vesicles are and the different types

membrane-bound storage and shipping containers. the vesicles that ship and store cellular products enclose and transport the products of the ER and Golgi apparatus. the contents of each vesicle depend on certain proteins in the membrane that act as "shipping labels." secretory vesicles contain products destined for export from the cell. they generally derive from the golgi apparatus membrane. endocytotic vesicles are the structures that enclose bacteria and raw materials from the extracellular environment and bring them into the cell by endocytosis. there are also peroxisomes and lysosomes that are vesicles that contain enzymes so powerful they have to be kept inside membrane to avoid damaging the cell

microvilli

microscopic projections of plasma membrane, they are an effective way to increase surface area relative to volume. it is especially common in cells that transport substances into and out of the body

anabolism

molecules are assembled into larger molecules that contain more energy. this process requires energy. ex. the assembly of a protein.

peroxisome

organelle that destroys toxic cellular waste

golgi apparatus

organelle that refines, packages, and ships macromolecular products. it's the cell's refining, packaging, and shipping center.

mitochondria

organelles responsible for providing most of the usable energy. the cell's "power plant." their number within the cell varies according to the energy requirements of the cells. they have a smooth outer membrane and a inner membrane with folds containing hundreds of protein enzymes.

metabolic pathways

organization of chemical reactions into orderly and predictable patterns. some are linear, in which the product from one chemical reaction becomes the substrate for the next chemical reaction. others are cyclical in which the substrate enters and the product molecules exit, but the basic chemical cycle repeats over and over again. there are two main types of metabolic pathways - anabolism and catabolism. important facts: 1. nearly every chemical reaction requires a specific enzyme. the cell regulates and controls the rates of chemical reactions through the specificity and availability of key enzymes. 2. the metabolic activities of a living cell require a lot of energy (for building complex macromolecules and active transport)

phospholipids in the plasma membrane

particular type of lipid with a polar head and neutral nonpolar tail. in the plasma membrane, two layers of these lipids are arranged so that the nonpolar tails meet in the middle of the membrane. as a result, the polar heads face the watery solutions outside and inside of the cell.

gated channels

particularly important in regulating the transport of ions (sodium, potassium, and calcium) in cells that are electrically excitable, such as nerve cells.

smooth endoplasmic rediculum

primary site of macromolecule synthesis other than proteins

rough endoplasmic reticulum

primary site of protein synthesis by ribosomes. ribosomes that are attached release their proteins into the folds of the ER.

glycoproteins

protein in the plasma membrane that typically have a carbohydrate group component, like an id tag for the cell. also can attach to microtubules and microfilaments in the cytoskeleton

channels in the cell membrane

proteins that span the entire lipid bilayer and allow passive transport by diffusion

receptor proteins

proteins that span the plasma membrane and can receive and transport information across the cell membrane. the information received generally causes something to happen within the cell even though no molecules cross the membrane

preparatory step

pyruvate enters the mitochondria and is converted to acetyl CoA, a 2-carbon acetyl group that is joined with coenzyme A. two additional NADH molecules are formed and acetyl CoA delivers the acetyl group to the next stage.

cytosol

semifluid ged material inside the cell

centrioles

short, rodlike microtubular structures located near the nucleus that are involved in cell division. they participate in alighning and dividing the genetic material of the cell

exoocytosis

similar to endocytosis, the process of moving material out of the cell. vesicles fuse with the plasma membrane, expelling its contents outside of the cell.

ribosomes

small structures composed of RNA and certain proteins that are either floating freely in the cytoplasm or are attached to the endoplasmic reticulum. they are responsible for making specific proteins. they assemble amino acids into proteins by connecting the appropriate amino acids in the correct sequence according to an RNA template

endocytosis

some molecules are too big to be transported through proteins or through the cell membrane. the process of moving larger amounts of materials. this moves materials into the cell. molecules outside of the cell are surrounded by a pocket formed by an infolding of the plasma membrane which pinches off, forming a vesicle within the cell

cytoskeleton

structural framework for the cell, made up of fibers called microtubules and microfilaments

glycolysis

the 6-carbon glucose molecule is split into two 3-carbon pyruvate molecules. energy is required to get the process started. this step occurs within the cytoplasm. 2 ATP are produced. it also produces hydrogen ions and electrons that are picked up by the coenzyme NAD+ to become NADH.

electron transport system

the NADH and FADH2 move to the inner membrane of the mitochondria and release the hydrogen ions and electrons. the electrons are transferred sequentially from one protein carrier molecule to another. the transfer allows the energy in the electrons to be released in manageable quantities. each time an electron is transferred, the carrier molecule acquires some of its energy and transports the H+ from the inner membrane to the space between the two membranes and the electron loses energy. this creates a higher concentration of H+ on one side of the inner membrane. however, H+ can only diffuse through ATP synthase, a special enzyme that uses the diffusion of H+ to catalyze the synthesis of ATP from ADP and Pi. the process requires oxygen to bond with the Hydrogen and electrons to maintain the rate of diffusion

phosphorylation

the addition of a phosphate group.

hypotonic

the concentration of solutes in the extracellular fluid is lower than the intracellular fluid. water enters the cell and causes it to swell. most cells when put in water will cause the cell to burst

hypertonic

the concentration of solutes is higher in the extracellular fluid than the intracellular fluid. water diffuses out of the cell and the cells shrink. eventually this impairs normal function and the cell dies

osmotic pressure

the fluid pressure required to exactly oppose osmosis

nucleus

the information center of a cell, it is an organelle that contains most of the cell's genetic material in the form of long molecules of DNA. the outside of the nucleus consists of a double-layered membrane called the nuclear membrane. the nuclear membrane is bridged by nuclear pores, too small for DNA to pass through but big enough to allow RNA and certain small proteins to pass through

describe diffusion through the lipid bilayer

the lipid bilayer of the plasma membrane allows molecules free passage. small, uncharged, nonpolar molecules can diffuse through. two important molecules that pass through this process are O2 and CO2 both involved in metabolism

facilitated transport

the molecule attaches to a membrane protein, triggering a change in the protein's shape or or orientation that transfers the molecule to the other side of the membrane and releases it there. once the molecule is released, the protein returns to its original form. the protein used in this process is called a transport protein. it is highly selective for particular substances and the direction of movement is always from a region of higher concentration to one of lower concentration

diffusion

the movement of molecules from one region to another as the result of the random collisions of molecules with other molecules.

osmosis

the net diffusion of water across a selectively permeable membrane is called osmosis

selectively permeable membrane

the plasma membrane allows only some substances to cross by diffusion, not other. it is highly permeable to water, but not to all ions and molecules.

active transport

the process moves substances through the plasma membrane against their concentration gradient. this requires the expenditure of energy. accomplished by proteins that span the plasma membrane and have access to some source of energy.

oxidative phosphorylation

the process of producing ATP from ADP using energy from the electrons as they are transported from one molecule to another.

tonicity

the relative concentrations of solutes in two fluids. because water can diffuse across the cell membrane so easily, the ability of a human cell to control its volume also depends on the tonicity of he extracellular fluid

substrate

the starting material for a chemical reaction

metabolism

the sum of all the chemical reactions in the organism

proteins in the plasma membrane

they act like doors, providing the means for transporting molecules and information across the plasma membrane. a few membrane proteins anchor the cell's internal scaffold-like support network while others span the entire membrane and others protrude from only one surface.

endocytotic vesicles

they enclose bacteria and raw materials from the extracellular environment and bring them into the cell by endocytosis

microfilaments

thin, solid fibers composed of protein, makes up the cytoskeleton of a cell

cholesterol in the plasma membrane

this increases the mechanical strength of the membrane by preventing it from becoming either too rigid or too flexible. It also prevents the phospholipids from moving around too much and helps to anchor the proteins within the membrane

microtubules

tiny, hollow tubes that are part of the cytoskeleton of a cell

lysosomes

vesicles that contain powerful digestive enzymes. they fuse with endocytotic vesicles within the cell, digesting bacteria and other large objects. they also perform certain housekeeping tasks, such as dissolving and removing damaged mitochondria and other cellular debris. when their task is complete, they become residual bodies of compacted waste that is usually eliminated from the cell by exocytosis

describe diffusion through channels

water and many ions diffuse through channels. the sizes and shapes, as well as the electrical charges on the various amino acid groups that line the channel, determine which molecules can pass through. some channels are open all the time, while others are "gated," meaning they can open and close under certain conditions.