Biology Exam Two

unified cell theory

one or more cells comprise all organisms, the cell is the basic unit of life, new cells arise from existing cells

all cells have:

plasma membrane, cytoplasm, DNA, ribosomes

prokaryote

a simple, mostly single-celled organism that lacks a nucleus, or any other membrane bound organelle. Most have a peptidoglycan cell walls and polysaccharide capsule

nucleiod

central part of a prokaryotic cell where the chromosome is located

prokaryotic cells are

0.1-5.0 micro meters in diameter while eukaryotic cells are 10 to 100 micrometers in diameter

As a cell gets larger, it becomes:

less efficient

eukaryotic cells

cell that has membrane-bound nucleus and several other membrane-bound compartments

Eukaryotic cells have:

a nucleus and membrane-bound organelles (mitochondria, vacuole, and chloroplast, endoplasmic reticulum, other chromosomes)

plasma membrane

phospholipid bilayer with embedded or attaches proteins, separates the cell's internal content from its surviving environment, controls passage of molecules

Phospholipid

a lipid molecule with two fatty acid chains and a phosphate-containing group

What limits prokaryote cell size?

Diffusion over long distances, DNA, ratio of SA:Volume

Microvilli

Fingerlike extensions of plasma membrane of apical epithelial cells, increase surface area, aid in absorbtion, exist on every moist epithelia, but most dense in small intestine and kidney

cytoplasm

entire region between the plasma membrane and the nuclear envelope, consisting of organelles suspended in gel-like cytosol, cytoskeleton, chemicals

nucleus

organelle composed of a double membrane that houses the cell's DNA and directs the ribosome and protein synthesis

nuclear envelope

the double-membrane structure that constitutes the outermost portion of the nucleus, is punctuated with pores

nucleoplasm

semi-solid fluid inside the nucleus that contains the chromatin and nucleolus

chromosomes

structure within the nucleus that comprises chromatin that contains DNA, linear in eukaryotes, singular and circular in prokaryotes

chromatin

protein-DNA complex that serves as the building material of chromosomes. Strands so that it can be read in order to send messages to proteins

nucleolus

region, darkly staining body w/in the nucleus that is responsible for assembling ribosome subunits

ribosomes

cellular structure that carries out protein synthesis. May float freely in cytoplasm or attach to cytoplasm or endoplasmic reticulum. Consists of two subunits (small and large). Receives orders from nucleus.

___ are particularly abundant in cells that

synthesize lost of protein, ex= pancreas

mitochondria

responsible for carrying out cellular respiration, resulting in producing ATP, high concentration in muscle cells

cellular respiration

process of making ATP using chemical energy in glucose and other nutrients, uses O and produces CO2 as waste

mitochondria

each membrane is a phospholipid bilayer embedded with proteins, Inner layer has cristae. ATP synthesis takes place on inner membrane

peroxisomes

small, round organelle that contains H2O2, oxidizes fatty acids and amino acids, detoxifies poisons, in liver cells

glycosomes

specialized peroxisomes in plants, are responsible for converting fat into sugars

vesicles

small, membrane-bound sac that functions in cellular storage and transport. Its membrane is capable of fusing with the plasma membrane and membranes of the ER and GA

vacuoles

membrane-bound sac, somewhat larger than a vesicle, functions in cellular transport and storage, does not fuse with membranes of other organelles

centrosome

region in animal cells made of 2 centrioles that serves as an organizing center for microtubules. Replicates itself after a cell divides, consists of two centrioles

centriole

cylinder comprised of nine triplets of microtubules. Nontubulin proteins hold triplets together, have a role in pulling duplicated chromosomes

lysosomes

animal cell's garbage disposal, functions as the cell's digestive component by breaking down proteins, lipids, other molecules

cell wall

covering comprised of various molecules that protects the cell, provides structural support and gives shape to the cell. Made of peptidoglycan and cellulose

chloroplasts

have own DNA and chromosomes, carry out photosynthesis, have inner and outer membranes

thylakoids

fluid-filled membrane sacs, each stack is a granum, interconnected and stacked w/in inner membrane

stroma

fluid enclosed by the inner membrane that surrounds the grana

chlorophyll

green pigment in chloroplasts that captures the light energy that drives light reactions of photosynthesis, in thylakoid

photosynthesis

Series of reactions that convert light energy, water, and CO2 into glucose and give off oxygen

central vacuole

plays a key role in regulating the cell's concentration of water in changing environmental conditions. Regulates plant cell's storage, holds H2O, plays significant role in cell growth because is site of macromolecule degredation, used to maintain pressure

endomembrane system

a group of membranes and organelles in eukaryotic cells that works together to modify, package, and transport lipids and proteins

Endomembrane system contains:

nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles and the plasma membrane.

endoplasmic reticulum

a series of interconnected membranous structures within eukaryotic cells that collectively modify proteins and synthesize lipids.
Rough ER and smooth ER.
ER membrane is continuous with nuclear envelope

Rough endoplasmic reticulum

region of the endoplasmic reticulum that is studded with ribosomes and engages in protein modification and phospholipid synthesis, abundant in cells that secrete proteins

Smooth endoplasmic reticulum

continuous with RoughER, has few ribosome units on cytoplasmic surface. Functions in the synthesis of carbs, lipids, steroid hormones, and detoxification of meds

sarcoplasmic reticuulm

special SER in muscle cells, responsible for storing Ca ions that are needed to trigger muscle cells coordinated contractions

Golgi apparatus

eukaryotic organelle comprised of a series of stacked membranes that sorts, tags, and packages lipids and proteins for distribution. Series of flattened membranes.

Fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane as a mosaic of phospholipids, cholesterol, proteins, glycoproteins, and glycolipids resulting in fluidity

Phospholipds are amphiphilic

molecule possesses a polar or charged area capable of interacting with hydrophobic and hydophilic environments
Are first major component

integral proteins

protein integrated into the membrane structure that interacts extensively with the membrane. Lipids and hydrocarbon chains and often spans the membrane (goes all the way across both layers of phospholipid bilayer)

peripheral proteins

protein at the plasma membrane's surface either interior or exterior, may serve as enzymes, structure, or part of cell recognition sites

carbohydrates

3rd major component of plasma membrane, always on cell's exterior surface and bound to lipids or proteins

Glycocalyx

carb components of glycolipids and glycoproteins, highly hydrophilic, attracts large amounts of H2O to cell's surface

cholesterol

only in animal cells. is a binder that acts bidirectionally, increases fluidity as low temps and decreases fluidity at high temps. Acts as a buffer. Stiff region stops fatty acids from coming apart and lysing at high temperature. Fluid region (H-C tail) has enough interaction to stop fatty acid's tails from sticking together in cold temperatures

Plasma Membranes Functions

1. dREefine outer border of all cells and organelles
2. Manage what enters and exits the cell
3. Receive external signals
4. Initiate cellular responses
5. Adhere to neighbors doing cells and exchange matter

More ___ fat in tropics

saturated

passive transport

method of transporting material through a semipermeable membrane, DOES NOT REQUIRE ENERGY. Substances move from high concentration to low concentration

Oligosaccharides

on exterior of cell membrane, deal in cell communication

Materials that can easily slip through membrane:

non-polar, lipid soluble low weight. Vitamins that are fat soluble, O2 and CO2 via simple diffusion.

Substances that can't pass through lipid core:

polar substances, ions, simple sugars, amino acids

diffusion

passive, single substance moves from high concentration to low concentration, transports materials across membrane within a cell.

filtration

variation of diffusion, material moves according to its concentration gradient through a membrane, enhanced by pressure

facilitated diffusion/transport

process by which material moves down a concentration gradient using integral membrane proteins. Shields polar materials from membrane's repulsive forces

transport proteins

membrane protein that facilitates a substances passage across a membrane by binding it, function as channels or carriers, transmembrane proteins

channel proteins

membrane protein that allows a substance to pass through its hollow core across the plasma membrane. Have hydrophilic domains exposed intra and extracellular and hydrophobic channel through core

aquaporins

channel protein that allows water through the membrane at a very high rate

carrier proteins

embedded in plasma membrane, protein that moves a substance across the plasma membrane by changing its own shape, specific for a single substance. Finite number

osmosis

the movement of free water through a semipermeable membrane according to the water's concentration gradient. Transports ONLY water. Will continue until the water's gradient goes to 0 or until the water's hydrostatic pressure balancces

In osmosis, water moves

from high concentration of water molecules to low concentration of water molecules

tonicity

amount of solute in a solution, describes how an extracellular solution can change a cell's volume by affecting osmosis, directly correlates with osmolarity

tonicity is the

relationship between outside and inside the cell

osmolarity

the total amount of substances dissolved in a specific amount of solution

low osmolarity means

A greater water concentration relative to concentration of solute

high osmolarity me ants

A lower water concentration relative to concentration of solute

hypotonic

when comparing two solutions, the solution with the lesser concentration of solutes

hypertonic

when comparing two solutions, the solution with the greater concentration of solutes

isotonic

when the concentration of two solutions is the same

osmoregulation

living thing's way of controlling effects of osmosis (plants have a cell wall)

turgor pressure

The pressure that water molecules exert against the cell wall

contractile vacuole

The cell structure that collects extra water from the cytoplasm and then expels it from the cell, in paramecia and amoebas

active transport

requires cell's energy, usually in ATP form

electrochemical gradient

a combined chemical and electrical force that produces a gradient, pushed molecules from low concentration to high concentration.

protein pump

active transport mechanism that works against electrochemical gradients

primary active transport

Active transport that relies directly on the hydrolysis of ATP. Ex= sodium potassium pump

secondary active transport

movement of material that is due to the electrochemical gradient established by primary active transport

transporter

specific carrier proteins or pumps that facilitate movement. Uniporter, symporter, antiporter

endocytosis

type of active transport that moves substances into a cell. The membrane invaginates, forming a pocket around the target particle. The pocket pinches off resulting in the particle containing itself in a new intracellular vesicle

phagocytosis

"cell eating", takes in large particles (anything but water)

clathrin

protein that coats the inward-facing surface of the plasma membrane and assists in the formation of specialized structures, like coated pits, for phagocytosis

pinocytosis

"cell drinking". Imports macromolecules that the cell needs from extracellular fluid, takes in molecules including water

potocytosis

variation of pinocytosis that uses caveolin

caveolin

protein that coats the cytoplasmic side of the plasma membrane and participates in the process of liquid update by potocytosis

receptor-mediated endocytosis

The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.

exocytosis

process of passing bulk material out of a cell into the extracellular fluid

Cytosleleton

helps the cell maintain its shape, helps the cell move, helps organelles within the cell move

microfilaments

the cytoskeletons' narrowest element, provides rigidity and shape to the cell and enables cellular movements

intermediate filaments

Threadlike proteins in the cell's cytoskeleton that are roughly twice as thick as microfilaments. Bears tension, supports cell-cell junctions, anchors cell to extracellular structures. No role in cell movement

microtubules

small, hollow tubes, the widest element, helps the cell resist compression, provides a track along which vesicles move through the cell, pulls replicated chromosomes to opposite ends. Comprised of alpha and beta tubulin

cilia

Hairlike projections that extend from the plasma membrane and are used for locomotion

extracellular matrix

The substance in which animal tissue cells are embedded, consisting of protein and polysaccharides.

Human body cells have how many chromosomes?

46, 23 pairs

diploid

A cell containing two sets of chromosomes (2n), one set inherited from each parent.