Unit 2 part 1

Prokaryote

evolution of first cells: 3.5 billion years ago

Eukaryote

evolution of first cells: 1.5 billion years ago

Prokaryote

Size of cells: smaller (1-10 mm)

Eukaryote

Size of cells: larger (100-1000 mm)

Prokaryote

Unicellular (less complex)

Eukaryote

Multicellular (more complex)

Prokaryote

Location of genetic information: Nucleoid region

Eukaryote

Location of genetic information: Nucleus

Prokaryote

DNA structure: Circular (usually one chromosome)

Eukaryote

DNA structure: Not circular (more than one chromosome)

Prokaryote

Reproductive strategy: asexual

Eukaryote

Reproductive strategy: sexual

Prokaryote

Oxygen requirement: anaerobic (does not need oxygen)

Eukaryote

Oxygen requirement: aerobic

Plant cells

have a cell wall surrounding the protoplasm

protoplasm

consists of all the living components of a cell

plasma membrane

The living components are bounded by a membrane known as ____

cytoplasm

All cellular components between the plasma membrane and the nucleus are known as _______

Cytosol

soup-like fluid where the organelles are dispersed

Cell Wall

o It is the most obvious plant cell structure observed with a microscope

o It defines the shape of the cell

cellulose

The cell wall is Made up mainly of ____but also consists of a matrix of hemicellulose, pectin, and glycoproteins

hemicellulose, pectin, and glycoproteins

Made up mainly of cellulose but also consists of a matrix of ,,_

Primary cell wall, secondary cell wall and middle lamella

Three parts of the cell wall

Plasma membrane

-The outer boundary of the living part of the cell

-It inhibits movement of some substances but at the same time allow free movement and even control movement of other substances into and out of the cell

Nucleus

-Control center of the cell

• Bounded by two membranes, which together constitutes the nuclear envelope

nucleus

o Most conspicuous object in a living cell→ appears as a grayish, spherical to ellipsoidal lump sometimes lying against the plasma membrane to one side of the cell or toward a corner

Nucleoplasm

granular-appearing fluid contained in the nucleus

Endoplasmic Reticulum

o Facilitates cellular communication and channeling of materials

o Synthesis of membranes for other organelles and modification of proteins from components assembled from elsewhere within the cell

Rough ER

ENDOPLASMIC RETICULUM

present in cells specializing in production of proteins and ribosomes are membrane bound

Smooth ER

ENDOPLASMIC RETICULUM

present in cells specializing in production of lipids; more tubular and not studded by ribosomes; production of steroid hormone and detoxification of organic chemicals

Ribosomes

-Rough ellipsoidal in shape with apparently varied and complex surfaces; does not have membranes

-Composed of 2 subunits that are composed of RNA and proteins

Sites of protein synthesis

Cytosolic ribosomes

RIBOSOMES

proteins made from these include enzymes

Membrane bound

RIBOSOMES

\proteins made from these facilitate or control the transport of ions and other substances through the plasma membrane

Dictyosomes

-Roundish, flattened-appearing sacs scattered throughout the cytoplasm

• Bounded by branching tubules that originate from the endoplasmic reticulum but are not directly connected to it

• -Modification of carbohydrates attached to proteins that are synthesized and packaged in the ER

• In dividing cells, they help build new primary walls after the nuclei have divided

• "Collecting, packaging, and delivery centers of the cell

Plastids

o Important energy transducing cell organelle found only in plants

Chloroplasts, Chromoplasts, and Leucoplasts

three types of plastid

Chloroplasts

PLASTIDS

stroma (colorless fluid matrix which contains enzymes; grana (contains thylakoids)

Chromoplasts

PLASTIDS

found in some cells of more complex plants; yellow, orange or red in color due to carotenoid pigments

Leucoplasts

PLASTIDS

common to higher plants; colorless and include amyloplasts and elaioplasts

Mitochondria

Powerhouse of the cell

-Responsible for the release of energy from organic molecules via cellular respiration

Cristae

MITOCHONDRIA

plate-like folds; increase the surface area available to the enzymes contained in the matrix fluid

Matrix fluid

MITOCHONDRIA

contains DNA, RNA, ribosomes, proteins, and dissolved substances

Microbodies

Smallest membrane-bound organelles

Peroxisomes

MICROBODIES

occurs primarily in leaves; metabolize hydrogen peroxide

Glyoxysomes

MICROBODIES

occurs in germinating oil-bearing seeds and young seedlings that grow from them; with enzymes that catalyze the breakdown of fatty acids into acetyl CoA

Vacuoles

Formed from the fusion of vesicles from the ER and the Dictyosomes

Cell sap

VACOULES

watery fluid that fills up the vacuoles; helps maintain pressures within the cell; contains salts, sugars, organic acids, and small quantities of soluble proteins as well as water soluble pigments (anthocyanins)

Tonoplasts/Vacuolar membranes

VACOULES

constitute the inner boundaries of the living part of the cell

microtubules

control the addition of cellulose to the cell wall; also involved

in cell division,

cytoskeleton

Network of filaments that forms a mechanical support system of the cell

microfilaments

CYTOSKELETON

role in the contraction and movement of cells in

multicellular animals
-Involved in the movement within a cell and in a cell's architecture

microtubules and microfilaments

cytoskeleton is Made up of two kinds of fibers

Microtubules

CYTOSKELETON

control the addition of cellulose to the cell wall; also involved in cell division, movement of cytoplasmic organelles, controlling the movement of vesicles containing cell wall components assembled by dictyosomes, and movement of flagella and cilia

Microfilaments

CYTOSKELETON

role in the contraction and movement of cells in multicellular animals; important in cytoplasmic streaming (cyclosis)

Plasmodesmata

Specialized junctions

Places where a hole is punched in the cell wall to allow direct cytoplasmic exchange between two cells

• Abundant in conducting cells and secretory cells (nectar glands and oil glands) but not present in water conducting tissues (at maturity, they have no living material to share between them)

The Cell Cycle

Set of processes that foster cell growth and division
-Complete only in cells that divide

Zygote

first dividing cell in the life history of the plant; formed from the union of sperm and egg; grows into a preembryo (via cellular division and expansion)

Meristems

specialized regions in the pre-embryo; capable of undergoing cell division

Interphase

living cells that are not dividing; chromosomes are not visible with the light microscopes; characterized by intervals known as Gap 1, Synthesis, and Gap II; longest period of the cell cycle since meristematic cells spend 90% of their time in this phase

G1

lengthy and begins immediately after a nucleus has divided; cell increases in size and ribosomes, RNA, and substances that inhibit or stimulate the S period that follows are produced

S

DNA replication (duplication) takes place

G2

Mitochondria and other organelles divide, and microtubules and other substances directly involved in mitosis are produced; where coiling and condensation of chromosomes begin

Mitosis

initiated with the appearance of a ring-like pre-prophase band of microtubules just beneath the plasma membrane
-Occurs in specific regions or tissues called meristems

Prophase, Metaphase, Anaphase, and Telophase

stages of mitosis

PROPHASE

Chromosomes condense into their familiar rod-like configuration

-Chromosomes become shorter and thicker; nuclear envelope fragments, and nucleolus disintegrates

-At the end of prophase, spindle fibers consisting of microtubules have developed

METAPHASE

Alignment of the chromosomes in a circle midway between the 2 poles around the circumference of the spindle and in the same plane as that previously occupied by the pre-prophase band
-Chromosomes composed of paired chromatids that are ultimate product of DNA replication

ANAPHASE

Briefest of the phases

-Involves the sister chromatids of each chromosome separating and appearing to be pulled to opposite poles

TELOPHASE

-Each group of daughter chromosomes becomes surrounded by a reformed nuclear envelope

-Daughter chromosomes become longer and thinner and finally become indistinguishable

CYTOKINESIS

Sudden appearance of a pucker or cleavage furrow on the cell surface→ furrow rapidly deepens and spreads around the cell until it completely divides the cell into two.

• Final step of cell division in which the cytoplasm of a mother cell is partitioned into two daughter cells