Plant cell components

Chromoplasts

lack chlorophyll contain carotenoid pigments, may function in attracting insects and other animals for cross-pollination and seed and fruit dispersal.

Leucoplasts

lack pigments some (amyloplasts) store starch, others from oils.

Amyloplasts

a type of leucoplast, involved in synthesis and long-term storage of starch in seeds and storage organs, eg. potato tubers

Proplastids

undifferentiated plastids, may form prolamellar bodies. Precursors of other plastids.

Grana

stack of thylakoids. (singular: granum)

Thylakoids

sheet-like membrane bound structure

Peroxisomes

surrounded by a single membrane. Sometimes contain crystalline protein bodies.

Peroxisomes

- Contain enzymes for a variety of processes such as photorespiration and conversion of fats to sucrose using glyoxysomes.

Peroxisomes

in green leaves, … are closely associated with mitochondria and chloroplasts

Mitochondria

surrounded by a double-membrane envelope. The inner membrane is folded into cristae Contains their own DNA and ribosomes

Mitochondria

Site of cellular respiration.

Rough endoplasmic reticulum

abundant in cells that store proteins

Rough endoplasmic reticulum

consists of flattened sacs (cistemae)

Smooth endoplasmic reticulum

abundant in cells that secrete lipids

Smooth endoplasmic reticulum

lacks ribosomes and is largely tubular in form

Cytoskeleton

complex network of protein filaments, consisting of microtubules and actin filaments.

Cytoskeleton

involved in cell division, growth, and differentiation

Microtubules

cylindrical structures composed of tubulin.

Microtubules

involved in cell plate formation, deposition of cellulose microfibrils, and directing the movement of Golgi vesicles and chromosomes

Actin filaments (microfilaments)

filamentous structures composed of tubulin

Actin filaments (microfilaments)

involved in cytoplasmic streaming and the movement of nucleus and organelles.

Golgi apparatus

consist of five to eight stacks of flattened, disk-shaped sacs, or cisternae.

cisternae

stacks of flattened, disk-shaped sacs, or ---

Golgi apparatus

consists of many separate stacks that remain active during mitosis and cytokinesis.

Golgi apparatus

involved in the synthesis and secretion of noncellulosic polysaccharides (hemicelluloses and pectins) destined for Incorporation into the cell wall.

Golgi apparatus

process and secrete glycoproteins that are transferred to them from the rough endoplasmic reticulum, via transition vesicles.

cell division

Cells reproduce by a process known as ---, in which the contents of a cell are divided between two daughter cells

Mitosis

The process of nuclear division, where the duplicated chromosomes are separated into two identical sets.

Prophase

Chromosomes condense, and the mitotic spindle begins to form.

Prometaphase

The nuclear envelope breaks down, and spindle fibers attach to the chromosomes.

Metaphase

Chromosomes line up at the … plate (middle of the cell).

Anaphase

Sister chromatids separate and move to opposite poles of the cell.

Telophase

Nuclear envelopes reform around the two sets of chromosomes, and the chromosomes begin to decondense.

Cytokinesis

the division of the cytoplasm

Interphase

This is the preparatory phase where the cell grows and prepares for division. It consists of three sub-phases

M phase

The two sets of chromosomes are separated (mitosis) and the cell divides (cytokinesis).

G₁ phase

Cell doubles in size; organelles, enzymes, and other molecules increase in number.

G₁ checkpoint

is the main decision point for a cell - that is, the primary point at which it must choose whether or not to divide.

S phase

DNA replicated and associated proteins synthesized; two copies of cell's genetic information now exist.

G₂ phase

Structures required for cell division begin to assemble; chromosomes begin to condense.

G₂ checkpoint

ensures that the cell has successfully completed DNA replication and that the replicated DNA is undamaged before proceeding to cell division. This checkpoint is essential for maintaining genomic stability and preventing the proliferation of cells with damaged DNA.

Cytokinesis

the division of the cytoplasm.

Cytoplasm

is divided by a cell plate that begins to form during mitotic telophase.

Phragmoplast

an initially barrel-shaped system of microtubules that forms between the two daughter nuclei in early telophase.

Cell Theory

Proposed by Matthias Schleiden and Theodor Schwann in 1839.

Cell Theory

All organisms are made up of cells. New cells are formed from pre-existing cells. Cells provide the basic unit of life.

single cells

unicellular organisms

Microscope

What instrument to use to study cells?

Micrometer

µm

Light microscopes

increase magnification as light passes through a series of transparent lenses.

Light microscopes

presently made of various types of glass or calcium fluoride crystals.

Electron microscopes

Provides detailed images of tiny structures within cells.

small, view

The term microscope is a combination of two words: micro, meaning "?," and scope, meaning "?."

Microscope

This instrument is designed to produce magnified visual or photographic images of objects too small to be seen by the naked eye.

Light Microscopes

the term light refers to the process by which light transmits the image to the eye.

Dissecting microscopes (stereomicroscopes)

Allow three-dimensional viewing of opaque objects.

Focus knob

Used to adjust the clarity or sharpness of an image, bringing it into focus.

Lighting control

Used to regulate the intensity or type of illumination for viewing a specimen or subject.

Eyepieces

The parts through which one views the magnified sample.

Diopter

An adjustment ring on one of the eyepieces, used to compensate for differences in vision between the viewer's eyes.

Stereo head

The upper part of the microscope that houses the optical components and eyepieces, providing a three-dimensional view.

Top lighting

An illumination source positioned above the stage to illuminate opaque samples.

Stage clip

A mechanism used to hold the sample or slide securely in place on the stage.

Stage plate

The platform on which the sample is placed for observation.

Compound microscopes

require that specimens be sliced thin or transparent to allow light to pass through, enabling observation of fine details.

Base

usually U- or V-shaped. This is where the microscope firmly rests.

Arm

connects the base and the body tube together. It serves as a handle for carrying the microscope.

Stage

the platform that holds/supports the slide containing the specimen. It has an opening at the center that allows light to pass from below into the specimen for study.

Pillar

the support or post of the base where the arm is attached

Stage clips

hold the specimen firmly on the stage.

Substage

found below the stage; it holds the Abbe condenser above and the iris diaphragm below.

Body tube

the cylinder that attaches the draw tube into the microscope and acts as the passageway of light from the objective to the eyepiece

Coarse adjustment

upper, larger knobs used to bring an object into focus only while it is being viewed under the low-power objective (LPO)

Fine adjustment

lower, smaller knobs for the slow movement of the body tube when focusing under the high-power objective (HPO) and other high-powered lenses

Revolving nosepiece

carries the objectives. Turned to select the appropriate objective. The lenses must be "clicked" in place for the field to be visible.

Draw tube

the smaller cylinder attached to the upper part of the body tube that holds the ocular

Eyepiece or Ocular

detachable cylinder located at the upper end of the tube. It may have a line inside that serves as a pointer and rotates as the ocular is rotated.

Objectives

usually, an ordinary laboratory microscope has two or three objectives attached to the revolving nosepiece. These are the scanner, and the low- and high-power objectives.

Scanner objective

the shortest cylinder with a very large opening. It is provided with a large lens for very low magnification and is used to observe a much wider field of the object. It is usually marked "5x."

Low power objective

shorter cylinder with a large lens opening. It is used to observe the general outline and locate the various parts of the specimen. It is focused by using the coarse adjustment. 10x.

High power objective

longer cylinder with a small lens opening. It is equipped with lenses of higher magnifying power and is used to study the detailed parts of the specimen. It is focused by using the fine adjustment knob. 40x.

Oil immersion objective

longest cylinder with a very small lens opening. It is equipped with very small lenses for very high magnification and is used to study the details of specific parts of the specimen. A small drop of special oil is needed so that the light passing through it is uniformly distributed, or dispersed. 100x.

Mirror

planar on one side and concave on the other. It is used to reflect light through the object and the lenses of the eyes. The concave side of the mirror is used for natural light, while the flat side is used for artificial light. Caution: Never use direct sunlight, as it may damage the lenses of the microscope and also injure your eyes.

Condenser

located on a substage held in place by a rack. It is used to condense or concentrate the light reflected from the mirror onto the object or specimen being examined.

Electron microscopes

a microscope that can magnify very small details with a high resolution. Its high magnifying capacity is due to the use of electrons rather than light to scatter off material, magnifying at levels of more or less 500,000 times the original size.

Transmission electron microscopes

can produce magnifications of 200,000 or more times, but the material to be viewed must be sliced extremely thin and introduced into the column's vacuum

Scanning electron microscopes

usually do not attain such high magnifications (30 to 10,000 times is the usual range) but surface detail of thick objects can be observed when a scanner makes the object visible on a cathode tube like a television screen

before a nucleus

Prokaryote means "?"

Archaea and bacteria

Examples of prokaryotes

Features:

1 to 10 micrometers

Cell size of a prokaryote

Absent

Nuclear envelope of a prokaryote. Absent or present?

Circular, In nucleoid

DNA of a prokaryote

Absent

Organelles (e.g., mitochondria and chloroplasts) of a prokaryote. Absent or present?

Absent

Cytoskeleton (microtubules and actin filaments) of a prokaryote. Absent or present?

with a true nucleus

Eukaryote means "?”

Protists, fungi, plants, animals

Examples of eukaryotes

Features:

Cell size of eukaryotes

5 to 100 micrometers: longer than 100 micrometers

Present

Nuclear envelope of a prokaryote. Absent or present?