CH. 2 - Cells: The Living Units

scientist that first observed plant cells

Robert Hooke

two scientists that asserted that all living things are made from cells

Matthias Schleiden and Theodor Schwann

asserted that cells arise from other cells — challenged “spontaneous generation”, which proposed that organisms can arise from nonliving matter

Rudolf Virchow

the outer boundary of a cell; the “fence” of the cell that selectively allows materials to pass through and separates intracellular fluid with extracellular fluid; some proteins have ability to act as receptors

plasma membrane

where most organelles and the nucleus is contained within the cell

cytoplasm

controls cellular activities in the cell’s center

nucleus

two parallel membranes separated by fluid-filled space; pores penetrate the nuclear envelope and allow large molecules to pass in and out of nuclear

nuclear envelope

in the center of the nucleus that contains parts of several chromosomes; site of ribosomal subunit assembly

nucleolus

DNA plus proteins form

chromatin

DNA wraps around this protein to form a nucleosome

histone protein

looks like beads on a string; active region of DNA where genetic code is copied onto mRNA in transcription

extended chromatin

Tightly coiled nucleosomes that are an inactive form of chromatin

condensed chromatin

highest level of organization of chromatin

chromosomes

long, preparatory stage of the cell cycle where a cell grows, performs its normal functions, and copies its DNA before dividing

interphase

first stage of interphase where cell is metabolically active, makes proteins and grows rapidly, and variable in length; centrioles begin to replicate near the end of this stage

G1 phase

second stage of interphase where DNA replicates and ensures that daughter cells receive identical copies of the genetic material (chromatin extended)

S phase

Final stage of interphase where centrioles finish copying themselves and enzymes needed for cell division are synthesized; is brief

G2 phase

G1 checkpoint assesses ____ ____ before DNA synthesis

cell size

G2 and M checkpoint checks for ___ ____ and accuracy of ______

cell size, replication

cell divides; after interphase

M phase

division of nucleus; chromosomes are distributed to two daughter nuclei

mitosis

First stage of mitosis where chromatin threads condense into chromosomes; centrioles begin pairs separate from one another and mitotic spindle forms

early prophase

chromosomes are made up of two threads called ______

chromatids

First stage of mitosis where centrioles continue moving away from each other; nuclear membrane fragments

Late prophase

second stage of mitosis where chromosomes cluster at the middle of the cell

metaphase

third phase of mitosis where centromeres of chromosomes split

anaphase

stage where ring of contractile actin and myosin filaments constrict to pinch cell in two; cells move into interphase

cytokinesis

cells that connect body parts or cover and line organs; makes and secretes protein component of fibers

fibroblast

cells that connect body parts or cover and line organs; unique shape that allows maximum number of cells to pack together

epithelial cell

cells that connect body parts or cover and line organs; concave shape provides surface area for uptake of the respiratory gases

erythrocyte

cells that move organs and body parts; elongated and filled with abundant actin and myosin filaments so they can shorten forcefully

skeletal and smooth muscle cells

cell that stores nutrients; spherical shape produced by large lipid droplet in cytoplasm

fat cell

cell that fights disease; moves through tissue to reach infection site

macrophage

cell that gathers information; long processes for receiving and transmitting messages

neuron

theory of aging that states damage is from byproducts of cellular metabolism; build up and damage essential molecules of cells

free radical theory

theory of aging that states a decrease in population of energy by mitochondria weakens and ages our cells

mitochondrial theory

theory of aging that states aging is programmed by genes; telomeres are structures that limit the maximum number of times cells can divide and telomerase prevents telomeres from degrading

genetic theory

constructed of proteins and ribosomal RNA; not surrounded by a membrane; site of protein synthesis “assembly line”

ribosome

a part of the production division that has two types that 1. produce proteins and 2. metabolizes lipids and stores calcium, respectively

endoplasmic reticulum

packages proteins for use either within or outside of the cell

golgi apparatus

membrane-walled sacs containing digestive enzymes, digest unwanted substances, “demolition crew”

lysosome

make energy, contains some maternally inherited DNA

mitochondria

enzymes neutralize free radicals and break down poisons, “toxic waste removal system”

peroxisomes

maintains cell shape and structure and transport materials within the cell

cytoskeleton

list rods of the cytoskeleton in ascending order (…<…<…)

microfilaments<intermediate filaments<microtubules

filaments of contractile protein actin that are used during cell movement, muscle contraction, and cytokinesis

microfilaments

protein fibers are stable and responsible for structural support, mechanical strength, and nuclear lamina

intermediate filaments

cylindrical structures made of proteins that are highly dynamic and responsible for vesicle transport, mitotic spindle, and cilia/flagella

microtubules

spherical structure in the cytoplasm composed of centrosome matrix and centrioles

centrosome

paired cylindrical bodies that act in forming cilia, flagella, and the mitotic spindle

centrioles

temporary structures in cytoplasm; may consist of pigments, crystals of protein, and food stores (liquid droplets and glycosomes)

cytoplasmic inclusions

found in liver cells and fat cells

lipid droplets

store sugar in the form of glycogen

glycosomes

plasma membrane consists of a _____ __layer; head is polar (attracted to water) and tail is nonpolar (avoids water)

lipid bilayer

a membrane protein that is firmly imbedded in lipid bilayer; most are transmembrane proteins that span the whole width of the membrane

integral protein

membrane protein that is loosely attached to membrane surface and include a network of filaments to support structure from cytoplasmic side

peripheral protein

formed by short chains of carbohydrate molecules that attach to integral protein

glyoproteins

sugars from glycoproteins project from external cell surface to form a “cell coat”. Used to help cells bind when they come together. Also acts as a biological marker to be recognized

glycocalyx

small, uncharged molecules (oxygen, CO2, fat-soluble molecules) can pass freely from more concentrated area to less concentrated area

simple diffusion

water-soluble and charged molecules (glucose, amino acids, ions) use ____ ____ through an integral protein to go from more concentrated area to less concentrated area

facilitated diffusion

molecules use ____ ____ to move against concentration gradient using energy

active transport

macromolecules use a different set of process called…

bulk/vesicular transport

Type of bulk transport by which large particles and macromolecules enter cells

endocytosis

Type of endocytosis where cell engulfs macromolecules (cell eating)

phagocytosis

Type of endocytosis where cell engulfs dissolved substances that bind to the cell membrane prior to internalization (cell drinking)

pinocytosis

Type of endocytosis where plasma proteins bind to certain molecules, invaginates and forms a coated pit, pinches off to become a coated vesicle; how insulin, other hormones, enzymes, and low-density lipoproteins enter cells

receptor-mediated endocytosis

Type of bulk transport that moves substances out of the cell

exocytosis

jellylike fluid in which other cellular elements are suspended; consists of water, ions, enzymes, and free ribosomes that make soluble proteins

cytosol