BISC1111 - Chapter 6 - Cell Structure and Functions

What do prokaryotes and eukaryotes have in common?

Cytoplasm, chromosomal material, plasma mebrane, ribosomes

Prokaryotic cells

cells without a nucleus or other membrane-bound organelles. Their DNA is located in a region called the nucleoid

Eukaryotic cells

Contain a nucleus where DNA is stored and other organelles that are bound by membranes.

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Cytosol

The semifluid soluble portion of the cytoplasm, which includes molecules and small particles, such as ribosomes, but not the organelles covered with membranes.

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells. It allows oxygen, nutrients, and waste to pass through in order to service the cell's volume

Mitochondria

The site of cellular respiration, the metabolic process that uses oxygen to generate ATP

Chloroplasts

Capture energy from sunlight and use it to produce food for the cell; site of photosynthesis

endosymbiont theory

explains that an early ancestor to eukaryotic cells engulfed an oxygen-using non-photosynthetic prokaryotic cell. The engulfed cell would then go on to form a relationship with the engulfer, eventually leading to eukaryotic cells

What do mitochondria and chloroplasts have in common?

Both have a double membrane, circular DNA and free ribosomes, and independent growth within the cell

Endocytosis

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

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells in order to make food vacuoles

Pinocytosis

A type of endocytosis in which the cell ingests extracellular fluid into tiny vesicles and its dissolved solutes.

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

What happens to the receptors in receptor-mediated endocytosis once the material is ingested?

The receptors are recycled

Vesicle

A membrane bound sac that contains materials involved in transport of the cell.

Kinesin

A class of motor proteins that uses the chemical energy of ATP to "walk" toward the plus end of a microtubule. Used to transport vesicles, particles, organelles and chromosomes.

What are the three fibers that make up the cytoskeleton?

Microtubules, microfilaments, and intermediate filaments

Centrosome

A structure in the cytoplasm of animal cells that works as a microtubule-organizing center and is important during cell division. A centrosome has two centrioles.

Centriole

structure in an animal cell that helps to organize cell division

Microtubule

one of the small, tubular fibers that compose the cytoskeleton, and play a role in cell structure and movement

Microfilament

a fiber found inside eukaryotic cells that is composed mainly of the protein actin and that has a role in cell division

Cytokinesis

Division of the cytoplasm during cell division (microfilaments)

Cell crawling

A form of cellular movement involving actin filaments in which the cell produces bulges (pseudopodia) that stick to the substrate and pull the cell forward.

Intermediate filaments

Threadlike proteins in the cell's cytoskeleton that offer more permanent cytoskeleton fixtures that microfilaments and microtubules do. They shape the cell and hold chromosomes and organelles in place.

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

nuclear envelope

layer of two membranes that surrounds the nucleus of a cell, protecting it from the cytoplasm

What makes up the two membranes of the nuclear envelope?

Lipid bilayers

Nuclear pore

passageway for molecules into and out of the nucleus

Nuclear lamina

A netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus.

Chromosomes

Discrete, thread-like units that DNA is organized into during cell division

Chromatin

Substance found in eukaryotic chromosomes that consists of DNA and proteins tightly coiled around histones

Nucleolus

Found inside the nucleus and is the site of ribosomal RNA (rRNA) synthesis

Ribosomes

site of protein synthesis

Free ribosomes

produces proteins in the cytosol

Bound ribosomes

Produces proteins on the outside of the endoplasmic reticulum or the nuclear envelope

endomembrane system

regulates protein traffic and performs metabolic functions in the cell

Consists of:

> Nuclear envelope

> Endoplasmic reticulum

> Golgi apparatus

> Lysosomes

> Vacuoles

> Plasma membrane

Endoplasmic Reticulum

A system of membranes that is found in a cell's cytoplasm and that assists in the production, processing, and transport of proteins and in the production of lipids.

Smooth ER

That portion of the endoplasmic reticulum that is free of ribosomes.

Rough ER

That portion of the endoplasmic reticulum studded with ribosomes. This is the part that synthesizes proteins

What else does the ER do?

Synthesize lipids, detoxify drugs and poisons, and store calcium ions

Glycoproteins

Proteins made by the rough ER that are covalently bonded to carbohydrates

What are some of the rough ER's other features?

Distributing transport vesicles and acting as a membrane factory

Golgi apparatus

A system of membranes that modifies and packages proteins from the ER for export by the cell

Lysosome

cell organelle filled with enzymes needed to break down certain macromolecules in the cell

Where do the enzymes made in lysosomes work best?

In the acidic environment of the lysosome itself

cis side of golgi apparatus

receives products from the rough ER

Trans side of Golgi

Shipping side for the refined proteins in the golgi. Vesicles are pinched off here to travel to other sites

Autophagy

A process in which lysosomes decompose damaged organelles to reuse their organic monomers

Vacuoles

Large vesicles from the ER and the GA that store materials such as water, salts, proteins, and carbohydrates

Central vacuoles

found in many mature plant cells, hold organic compounds like salt, sap and water

Cristae

Folded result of the smooth membrane and an inner membrane of mitochondrion that houses the electon transport chain and the enzyme catalyzing the synthesis of ATP.

What are the two parts of the inner membrane of a mitochondria?

Intermediate space and mitochondrial matrix

Mitochondrial matrix

the space inside the inner membrane of a mitochondrion where some of the metabolic steps of cellular respiration are catalyzed in

Intermediate space

space between outer and inner membrane of a mitochondrion

Chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria

Thykaloids

membrane discs containing plant pigments; coin-like structures

Granum

A stack of thylakoids in a chloroplast

Stroma

fluid portion of the chloroplast; outside of the thylakoids

Peroxisomes

Produce hydrogen peroxide (H2O2) by utilizing enzymes that remove hydrogen from substances and adding them to oxygen

What do peroxisomes do with the H2O2 they produce?

Detoxify alcohol and other harmful compounds in the liver

Glyoxysomes

Only in plants—lipids are converted to carbohydrates for growth in emerging saplings

Cell wall

A rigid, extracellular structure that surrounds the cell membrane and provides support to the cell. ONLY IN PLANT CELLS.

What other organisms besides plants have cell walls?

Fungi, prokaryotes, and some protists

Primary cell wall

In plants, a relatively thin and flexible layer first secreted by a young cell.

Middle lamella

The thin film between the cell walls of adjacent plant cells. Contains a polysaccharide known as pectin

Pectin

a soluble gelatinous polysaccharide that is present in ripe fruits and is extracted for use as a setting agent in jams and jellies.

Secondary cell wall (in some cells)

added between the plasma membrane and the primary cell wall

Extracellular matrix

a collection of extracellular molecules secreted by animals to protect them given that they lack cell walls

What are some examples of extracellular matrices?

Collagen, proteoglycans, and fibronectin

Fibronectin

An extracellular glycoprotein secreted by animal cells that helps them attach to the extracellular matrix.

Proteoglycans

a glycoprotein consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells.

Collagen

structural protein found in the skin and connective tissue

cisternae

Flattened, membrane-bound compartments that make up the Golgi apparatus.

Flagella

long, whiplike tail found in one-celled organisms that aid in movement

Cilia

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