Cells

Chapter 3

Cells Alive

Overview of Cell Parts

Prefixes/Suffixes

• Cyt- cell

• Endo- in

• Hyper- above

• Hypo- below

• Inter- between

• Iso- equal

• Mit- thread

• Phag- eat

• Pino- drink

• -som - body

Now we are ready to review the cell

What is in the cell?

• Most of the cell space is Cytoplasm.

– Cytosol: Gel like fluid where most of the cells chemical reactions take place.

• Organelles: Mini cell organs that carry out specific job functions for the cell.

What is the biggest organelle?

• The nucleus

– The control center for the cell

– Contains DNA

• Contains the message that makes proteins

• Proteins run the cell.

– Contains the organelle= nucleolus

• Nucleolus makes RNA that carries out DNA’s instructions.

What surrounds the nucleus?

• The Phospholipid membrane

• Two membranes.

• Keeps DNA in

• Only RNA can leave

What are the major organelles?

• Ribosomes: rRNA. Where proteins are made. Usually on the rough ER.

• Endoplasmic Reticulum: – rough ER close to the nucleus, where

proteins are made– Smooth ER makes lipids. No rRNA

present.• Golgi Apparatus: Ships proteins and

lipids.

More organelles…

• Lysosomes: SOS. Contain digestive enzymes. Kill invaders and worn out cell parts.

• Mitochondria: Power house of the cell. Makes ATP (Body runs on ATP energy.)

• Cytoskeleton: Skeleton of the cell. Shape• Centrioles: Move Chromosomes during cell

division.• Microtubules: Basis for cilia and flagella

Mitochondria

Ribosome

Endoplasmic Reticulum

Golgi Apparatus

Cytoskeleton

Checkpoint

• What is the functional difference between cilia and flagella?

• What are the structural and functional differences between smooth and rough ER?

• Which organelles contribute to synthesizing protein hormones and packaging them into secretory vesicles?

Interactive Cell Parts

Cell Membrane Fluid-Mosaic Model

What surrounds the cell?

• The Plasma Membrane. Made out of Phospholipids.

• May have cilia or microvilli around the cell.

• Microvilli are in the back of your throat (filter air) and in your intestine (absorb food)

Why is the plasma membrane selectively permeable?

• Works as a barrier. Only allows certain things in or out of the cell.

• Means of protection.• Cells that can not do this are

dead or damaged.

Checkpoint

• List the three main parts of the cell and explain their functions.

• Why are membranes said to have selective permeability?

Membrane Transport

Pg. 47-52

• Active Transport: uses energy (ATP) to move molecules against the concentration gradient or to move large things.

• Passive Transport: uses NO energy to move molecules with the concentration gradient.

What are the two forms of cell transport?

What types of Passive transport does the body use?

• Diffusion: When molecules move from high to low or with the concentration gradient.–Perfume, food

coloring, etc. all do this.

Simple Diffusion

Diffusion through a gated membrane channel

What types of Passive transport does the body use?

• Facilitated Diffusion: Uses carrier proteins to move substances without energy with the concentration gradient.

• Filtration: water and solutes are forced through a plasma membrane. Happens in the Kidneys.

Osmosis

• Osmosis: a specialized form of diffusion which moves water from high to low across the plasma membrane.

Types of Solutions: Pg 50• Isotonic Solution: Same tonicity inside

and outside the cell. Cell stays the same size.

• Hypertonic Solution: Higher tonicity outside the cell. Cell shrinks.

• Hypotonic Solution: Lower tonicity outside the cell. Cell swells and “POPS”

Principles of osmosis applied to red blood cells

What types of Active Transport do you use?

• Solute Pumping: Require protein carriers and energy to move sugars, Amino Acids, and ions against the concentration gradient. (Sodium

Potassium pump used in Nerve cells)

Sodium-potassium pump

More Active Transport…• Bulk Transport: Substances too big to

pass through the plasma membrane. –Exocytosis: Large things exit the cells–Endocytosis: Large things enter the cell

• Phagocytosis: Cells that eat- white blood cell• Pinocytosis: Cells drink- intestine and kidneys

Phagocytosis

Checkpoint• How would having a fever affect body

processes that involve diffusion?• If 0.9% NaCl is isotonic saline solution for

red blood cells, would a 2% solution of NaCl cause the red blood cells to expand or shrink?

• What is the key difference between active and passive transport?

• In what ways are endocytosis and exocytosis similar and different?

How Proteins are Made

Pgs. 58-62

Overview

What are the names of DNA?

• Chromatin: Unwound DNA

• Chromosomes: Tightly wound DNA

The Basic Process of Making Protein

• DNA (In the Nucleus) is Transcribed into mRNA. (Transcription)

• RNA brings the message to the Rough ER where its Translated into a protein. (Translation)

Overview of transcription and translation

The Details: RNA(Ribonucleic Acid)

• There are three types of RNA• mRNA (messenger RNA)• rRNA (Ribosomal RNA)• tRNA (Transfer RNA)• RNA is Single Stranded, sugar is RIBOSE• The Nitrogen bases for RNA are…

– Adenine bonds to Uracil– Cytosine bonds to Guanine

The Story

• DNA is stuck in the nucleus. • RNA is made in the nucleolus. • mRNA transcribes or re-writes

DNA’s code in RNA and leaves the nucleus through nuclear pores.

• mRNA brings the message to the ribosome also known as rRNA.

The fairy tale continues

• Once mRNA is hooked onto the rRNA it needs the right amino acids to make a protein.–Remember 50 or more A.Acids make a

Protein!• tRNA carries amino acids to the rRNA and

hooks them onto the correct mRNA codon.–A codon is a three nucleotide sequence

(AUG)

How does the story end?

• When the stop codon is reached the Amino Acid chain falls off and rolls into a ball and becomes a protein.

• mRNA goes back to the nucleus to be reused.

• rRNA stays on the Endoplasmic Reticulum waiting for the next job.

• tRNA picks up new Amino Acids for the next job.

Transcription

Protein elongation and termination of protein synthesis during translation

Checkpoint

• If the DNA template had the base sequence AGCT, what be the mRNA base sequence?

• What is the difference between transcription and translation?

Chromosomes and Mitosis

Pg. 62-65

Two different Cell Divisions

• Meiosis- produces gametes or sex cells. New cells are different from the original cell.

• Mitosis- produces new body cells-like your toes. New cells are identical to original cell.

• Chromosomes: Tightly wound DNA. Resemble an X because two chromatids are held together.- Supercoiled.

• Centromere holds the chromosomes (Two sister Chromatids) together.

• Chromatid: A single tightly wound strand of DNA.

DNA in all of its fine forms:

And last but not least…• DNA is your genetic information. In the

shape of a double helix. The nucleotide pairs are: (Hydrogen bonds)–Adenine: Thymine–Cytosine: Guanine

• DNA is broken into segments called genes which code for proteins.

• Genes give you your physical characteristics.

Before Eukaryotic Cells Divide…

• Its chromosomes are replicated.• Happens through the process of DNA Replication.

DNA Replication:• DNA needs enzymes (protein) to copy or replicate

itself.• Double helix unwinds using DNA Helicase. • DNA Helicase breaks the hydrogen bonds.• Where the DNA breaks apart is called the

replication fork. DNA polymerase (another enzyme) adds nucleotides at this point.

How many Chromosomes do humans have?

• Each somatic cell or body cell has two copies of 23 chromosomes.

• One copy of the chromosomes (sex cells or gametes) have 23 chromosomes and are called haploid or n = 23.

• Two copies of the chromosomes (somatic cells) have 2n = 46.

There are two types of Chromosomes.

• Autosomal Chromosomes: or autosomes are not sex chromosomes.

• Sex Chromosomes: determine the sex of the individual. The male of the species determines the sex of the offspring. Women only have one X chromosome. Males have an X or a Y.

• XX is a girl• XY is a boy

Karyotypes: Pictures of your DNA.

• Why do we take pictures? To find mistakes

The 5 stages of the Cell Cycle

• G1: Cell Growth and Metabolism• S: DNA is copied• G2: Cell prepares for division.• Mitosis: Nucleus divides, cell

parts separate.• Cytokinesis: Cytoplasm divides

Mitosis: The Basic Steps• Prophase: DNA forms chromosomes.

Nuclear envelope disappears. In Animals spindle fibers form.

• Metaphase: Chromosomes move to the center of the cell- pulled by spindle fibers.

• Anaphase: Chromosomes are separated into chromatids. Spindles shorten pulling chromatids to opposite ends of the cell.

• Telophase: Nucleus reforms. Chromatids turn back into Chromatin. Spindles disappear.

Chromosomes

Cell Division

and Mitosis

After Mitosis

• Cytokinesis: Cytoplasm divides in half.

• Animals: The plasma membrane pinches in half= Furrow.

• Plants: A cell wall grows between the two new cells. Cell Plate.

When control of the Cell cycle is lost: Cancer is the outcome.

• Cancer: uncontrolled cell division or death.

• Read pg 66: Normal cells become cancerous.

Abnormal Cell Functioning - Cancer

• Malignant – uncontrolled cell division – carried by lymph or blood to other organs to develop secondary tumors (metastasis)

–Created by a mutation

•Carcinogens, ultraviolet light

• Benign – remain localized

Mitosis Interaction

Checkpoint

• In which phase of the cell cycle does DNA replication occur?

• Why must DNA replication occur before cytokinesis?

• When does cytokinesis begin?

Meiosis: The making of gametes• One cell eventually creates four

cells• Each cell is different from the

parent cell• Haploid• Meiosis goes through cell

division twice

The Stages of Meiosis• Prophase 1: Chromosomes are made and

the nucleus membrane disappears. • Homologous Chromosomes pair and

attach by centromeres.• Crossing-over occurs. Cross over is the

process of homologous chromosomes breaking off and exchanging parts. – This process is responsible for making

you unique!

Meiosis Animation

Why does Meiosis create genetic variation?

• Crossing over. Mixes up the traits on each chromosome.

• Independent assortment. You have 46 chromatids. ½ go to each new cell in Meiosis 1 and again in Meiosis II. No one knows which chromatids will go to which cell.

• Random Fertilization. Which egg and which sperm will meet? = a greater genetic variability.

Making Gametes: Different for different sexes.

• Sperm Formation• Spermatogenesis• One diploid germ

cell makes four haploid sperm cells.

• Occurs in the testis throughout the males adult life

• Egg formation: Ovum• Oogenesis• One diploid germ cell

makes one egg and three polar bodies.

• Egg must provide the food for the zygote (fertilized egg)

• Made in ovaries, most before birth

Sexual Reproduction: Two parents.

• Offspring is genetically different from parents.

• Great for environmental change. Easy to evolve.

• Meiosis can better repair damaged DNA

Checkpoint

• How does crossing-over affect the genetic content of the haploid gametes?

• How are haploid and diploid cells different?

• What are homologous chromosomes?

Sickle-Cell Anemia

• Most common genetic disorder among people of African descent

• Hemoglobin crystallizes when the oxygen levels are low and the red blood cells deform into sickles, which can clog and rupture capillaries causing internal bleeding

• Incurable

Chapter Quiz

Cell Case Study

Stem Cells

• Stem

• Cell

• Differentiation