Chapter 7 - Cell Structure and Function

nucleus

'Control center' of cell, meaning it controls cellular processes. Contains the genetic material/ DNA (coded instructions for making proteins & other important molecules).

ER is divided into two portions - rough endoplasmic reticulum (rough ER) & the smooth endoplasmic reticulum (smooth ER)

1. rough endoplasmic reticulum (rough ER): involved in the synthesis of proteins *found in cells that produce an abundance of proteins for export 2. smooth endoplasmic reticulum (Smooth ER) called so as ribosomes not found on its surface. Contains collection of enzymes that perform specialized tasks like detoxification of drugs & synthesis of membrane lipids. *found in liver cells

chromatin

A granular material inside the nucleus. This is made up of DNA bound to proteins. When the cell divides, this condenses into chromosomes.

cytoskeleton

A network of protein fibers that holds the cell together, helps the cell to keep its shape, and aids in movement - microfilaments & microtubules are the main protein filaments that make up the cytoskeleton.

cell wall

A strong supporting layer around the cell membrane in plants, algae, and some bacteria

cell membrane

A thin, flexible barrier that controls which substances can enter or leave the cell and provides protection and support.

chromosome

A threadlike structure located in a cells nucleus contains DNA and is passed from one generation to the next

prokaryote or prokaryotic cells:

A unicellular organism that lacks a nucleus - have genetic materials that is contained in the nucleoid. Examples of: bacteria

eukaryote or eukaryotic cells:

An organism whose cells contain a nuclei - these cells contain dozens of structures & internal membranes, many very specialized. Have a nucleus where DNA stored & separated from rest of cell. Examples of: Plants, animals, fungi & protists. * these cells can be seen as having two parts - the nucleus & the cytoplasm

vacuole

Cell organelle (saclike strucure) that store materials such as water, salts, proteins, and carbohydrates *in plants there is often a large central vacuole filled with liquid that makes it possible for them to hold leaves & flowers up.

mitochondria

Cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use. almost all eukaryotic cells, including plants, have one. Mitochondria are enclosed by two membranes - the inner and the outer; they contain their own genetic info in the form of small DNA molecules. *In humans almost all mitochondria come from the cytoplasm of the ovum, or egg cell.

cell

Collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life. **ALL cells have two characteristics in common: all have cell membrane, all contain DNA molecule *cells get energy from food molecules or from the sun

SYNTHESIS - what does that mean????

Combining of small molecules or substances into larger, more complex ones

osmosis

Diffusion of water through a selectively permeable membrane. What does diffusion mean?? movement/to move

lipid bilayer

Double-layered sheet that forms the core of nearly all cell membranes - a flexible structure that forms a strong barrier between cells and surroundings.

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference. Carried out by transport proteins or pumps found in the membrane.

osmotic pressure

For organisms to survive, they must have a way to balance the intact & loss of water. A Force produced by the pressure of water diffusing through a semipermeable membrane; the greater the difference in water concentration on either side of the membrane, the greater the osmotic pressure

microtubules

Hollow structures made of proteins called tubulins. Help maintain shape of cell. Big role in cell division where they form the mitotic spindle which helps separate chromosomes.

nuclear envelope

Layer of two membranes that surrounds the nucleus of a cell. - dotted with thousands of nuclear pores which allow material to flow in/out of nucleus

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels. No energy required. passive.

Scanning Probe microscopes

Produce images by tracing the surface of samples with a fine probe. Can operate in ordinary air & can show samples in a solution. *can observe a single atom

molecular transport

When small molecules and ions are moved across membranes that act like energy required pumps.

organ

a group of tissues that work together to perform closely related functions

Scanning Electron Microscopes (SEM)

a pencillike beam of electron is scanned over the surface of a specimen. Produces stunning 3D images of cells

endoplasmic reticulum (ER)

an internal membrane system in cells in which lipid components of the cell membrane are assembled along with some proteins and other materials that are exported from the cell.

Transmission Electron Microscopes (TEM)

are capable of revealing details 1000 more times smaller than those visible in light microscopes because electrons wavelengths are shorter than those of light. *must cut cell & tissue into ultrathin slices first because electron beams can only pass through thin slices.

Notes on Electron Microscopes (TEM & SEM)

because electrons are easily scattered by molecules in the air, samples in both type microscopes must be placed in a vacuum. Researchers chemically preserve samples first & then carefully remove all water before placing them in microscope**Electron microscopes can be used on NONliving, preserved cells & tissues.

SYMBIOSIS - what does that mean?

cooperation; mutual helpfulness - a relationship in which two species live closely together.

Robert Hooke

first scientist to use word "cell" in 1665. used early compound microscope to look at cork, a plant material & called chambers he saw "cells"

organ system

group of organs that work together to perform a specific function

tissue

group of similar cells that perform a particular function. most animals have 4 types of tissue: muscle, epithelial, nervous & connective.

cell theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

endosymbiotic theory

idea that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms -

tubulin

in animal cells tubulin is used to form the centrioles

Levels of organization in a multicellular organism

level 1: tissue level 2: organ level 3: organ systems These levels are interdependent & divide labor in ways that make life possible.

centrioles

one of 2 tiny structures located in the cytoplasm of animal cells near the nuclear envelope - they help organize cell division. NOT found in plant cells.

centriole

one of two tiny structures located in the cytoplasm of animals cells near the nuclear envelope

chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy. Plants & some other organisms have; surrounded by two membranes. They contain their own genetic info in the form of small DNA molecules. Contain chlorophyll.

exocytosis

process by which a cell releases large amounts of material

endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

pinocytosis

process by which cell takes in liquid from the surrounding environment

diffusion

process by which molecules tend to move from an area where they are more concentrated into an area where they are less concentrated **because diffusion depends upon random particle movements, substances diffuse across membranes without requiring the cell to use energy

phagocytosis

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

cilium (singular) cilia (plural) flagellum (singular) flagella (plural)

short hairlike projection/structures; they produce movement in many cells. can be very forceful - they are like oars on boat pushing & pulling through water

lysosome

small organelles filled with enzymes that break down or digest carbs, lipids & proteins so other parts of cell can use them. Also breakdown other lysosomes that have outlived usefulness lysosomes remove all the built up junk in the cell so not cluttered.

ribosome

small particles of RNA & protein found in the cytoplasm. Proteins are produced by ribosomes that follow instructions that are sent from the nucleus.

nucleolus

small, dense region within most nuclei in which the assembly of ribosomes begins

organelle

specialized structure that performs important cellular functions within a eukaryotic cell

Golgi apparatus

stack of membranes in the cell that modifies, sorts and packages proteins from the endoplasmic reticulum for storage in cell or for secretion outside of the cell. golgi apparatus sends proteins to the final destination throughout the cell or outside of the cell.

homeostasis

the maintenance of a controlled internal environment.

concentration

the mass of solute in a given volume of solution, or mass/volume

solution

the mixture of two or more substances

cell specialization

the process in which cells develop in different ways to perform different tasks. EX: in animals -Red blood cells are specialized to transport oxygen & cells. in plants - guard cells monitor the plants internal conditions

cytoplasm

the protein of the cell outside of the nucleus.

solute

the substances dissolved in the solution

microfilaments

threadlike structures made of a protein called actin. Form extensive networks & produce a tough flexible frameworks that support the cell. Also help the cell move.

Anton van Leeuwenhoek

used single-lens microscope to to observe pond water & other things. Discovered world of organisms even in drinking water.

hypotonic

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

hypertonic

when comparing two solutions, the solution wth the greater concentrate of solutes

equilibrium

when the concentration of a solute is the same throughout a solution. **even when equilibrium is reached, particles of a solution will still move about but there is no change in concentration.

isotonic

when the concentration of two solutions is the same