Life Science Review

http://www.allaboutmammals.com/label/biology.shtml

Chloroplast- The cell organelle in which photosynthesis takes place. In this organelle the light energy of the sun is converted into chemical energy. Chloroplasts are found only in plant cells not animal cells. The chemical energy that is produced by chloroplasts is finally used to make carbohydrates like starch, that get stored in the plant. Chloroplasts contain tiny pigments called chlorophylls. Chlorophylls are responsible for trapping the light energy from the sun.

Differences between Prokaryotic & Eukaryotic cellsBacterial cells also contain flagellum, plasmid and capsule.

Feature Prokaryote Eukaryote

Size Small about 0.5 micrometers

Up to 40 micrometers

Genetic material

Circular DNA (in cytoplasm)

DNA in form of linear chromosomes ( in nucleus)

OrganellesFew present, none membrane bound

Many organelles:• Double membranes e.g.:

nucleus, mitochondria & chloroplasts

• Single membrane e.g.: GA, ER & lysosomes

Cell wallsRigid formed from glycoproteins (mainly murein)

• Fungi: rigid, formed from polysaccharide, chitin.

• Plant: rigid, formed from polysaccharides. E.g.: cellulose.

• Animals no cell wall

Ribosome’s 70s 80s

Definitions and plant cell parts.Cytoplasm-gel like substance found in a cellChloroplasts-a green structure in a plantCell Wall-a stiff covering that protects plant

cellsNucleus-control center of the cellChromosomes-provides direction for cell to

followEndoplasmic Reticulum-transportation networkMitchondrion-produces energy in the cellVacuole-cell storage sac for food, waste and

water

Parts of the animal cell and definition.Vacuole-cell storage sac for food,waste, and

waterMitochondrion –produces energy in a cell

Chromosomes-provides direction for cells to follow

Nucleus-control center of a cellEndoplasmic Reticulum--transporation system

Cytoplasm-gel like substance found in a cell

Cell Membrane-surrounds cell material

Cells also carry out diffusion,passive transport active transport and osmosis.

Diffusion-movement of gases from higher concentrations to lower concentrations

Passive Transport-materials do not need energy to move from higher concentration to lower to a lower concentration

Active Transport-materials need energy to move from a higher concentration to lower concentration

Osmosis-water moving from higher concentration to a lower concentration

DNA is a double helix

• All DNA Is made up of 3 parts– Phosphate group – 5 sugar deoxyribose – Nitrogen Base

What are the four bases?

• Pyrimidine: Only one ring– Thymine (T)– Cytosine (C)

• Purines; 2 rings– Adenine (A)– Guanine (G)

The backbone is connected by covalent bonds.

hydrogen bond covalent bond

The bases are connected by hydrogen bonds.

Replication copies the genetic information.

• A single strand of DNA serves as a template for a new strand.

• The rules of base pairing directreplication.

• DNA is replicated during theS (synthesis) stage of thecell cycle.

• Each body cell gets acomplete set ofidentical DNA.

A Model used to show the possible ways genes can combine during fertilization.

Dominant and recessive alleles

are represented by letters.

A capital letter (T) is used for dominant alleles.

Punnett Squares

A lowercase letter (t) is used for recessive alleles.

The letters representing the alleles from one parent are placed along the top of the square.

T t

Punnett Squares

T t x T t

T t

T

t

Punnett Squares

Punnett Squares

Squares are filled by writing the letter at the top beside the letter on the side.

TT Tt

Tt t t

T t

T

t

Punnett Squares

The letters in each of the squares represents the Genotypes of the offspring that the parents could produce.

TT Tt

Tt t t

T t

T

t

TT

Tt

Tt

t t

The genotype (genetic makeup) can be used to predict the phenotype (physical appearance) of the offspring.

Punnett Squares

Genotype Phenotype

TT tall

Tt tall

Tt tall

t t short

Punnett Sqaures

Chromosomes, Genes, and Genetic Crosses

1. Homologous Chromosomes contain genes (locations) for the same traits

2. Traits are controlled by alleles (alternative forms of a gene).

3. Genotype refers to the alleles an individual receives at fertilization

4. Phenotype refers to the physical appearance of the individual.

5. Homozygous dominant genotypes =two dominant alleles for a trait. (BB)

6. Homozygous recessive genotypes =possess two recessive alleles for a trait (bb)

7. Heterozygous genotypes =one of each allele for a particular trait (Bb)

Punnett Squares

Probability: the ratio that a particular event could occur.

out of 4 offspring

3 would be tall

1 would be short

Punnett Squares:

•Help you keep track of traits.

•Predict genotype and phenotype.

•Calculate probability.

Cell Cycle

• During the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells, each with each of which then begins the cycle again.

• Interphase – time for growth and regular cell activity.

• Most of a cells life is spent in Interphase.

Mitosis

• The division of somatic or regular cells.• Its divided into 4 phases.• Remember Interphase is NOT part of Mitosis.

Prophase

• First stage of Mitosis• Chromatin condenses into chromosomes• Centrioles separate and a spindle fiber begins

to form.• Nuclear membrane breaks down

Metaphase

• Second Phase of Mitosis• Chromosomes line up in the middle of the cell.• Each chromosome is connected to a spindle

fiber.

Anaphase

• Third Phase of Mitosis• The sister chromatids separate into individual

chromosomes and move apart to opposite ends of the cell.

Telophase

• Fourth and Final Stage of Mitosis• Chromosomes gather at opposite ends of the

cell and lose their distinct shapes• Two new nuclear membranes have formed.

Cytokinesis

• The cytoplasm pinches in half.• Each daughter cell has an identical set of

duplicate chromosomes

Regulating the Cycle

• A protein call cyclin helps regulate the cell cycle in eukaryotic cells.

• They respond to internal and external events. These proteins are regulators.

When Things Go Wrong

• Cancer cells do not respond to the signals that regulate the growth of most cells.

• As a result, they form masses of cells called tumors that can damage surrounding tissues.

Meiosis KM 37

Reproduction• Asexual

– Many single-celled organisms reproduce by splitting, budding, parthenogenesis.

– Some multicellular organisms can reproduce asexually, produce clones (offspring genetically identical to parent).

Meiosis KM 38

Chromosomes

• Karyotype: – ordered display of an individual’s chromosomes.– Collection of chromosomes from mitotic cells.– Staining can reveal visible band patterns, gross

anomalies.

Meiosis KM 39

In humans …• 23 chromosomes donated by each parent (total =

46 or 23 pairs).• Gametes (sperm/ova):

– Contain 22 autosomes and 1 sex chromosome.– Are haploid (haploid number “n” = 23 in humans).

• Fertilization/syngamy results in zygote with 2 haploid sets of chromosomes - now diploid.

– Diploid cell; 2n = 46. (n=23 in humans)

• Most cells in the body produced by mitosis.• Only gametes are produced by meiosis.

Meiosis KM 40

Chromosome numbersAll are even numbers – diploid (2n) sets of homologous chromosomes!

Ploidy = number of copies of each chromosome. Diploidy

Meiosis KM 41

Meiosis – key differences from mitosis• Meiosis reduces the number of chromosomes by half.• Daughter cells differ from parent, and each other.• Meiosis involves two divisions, Mitosis only one.• Meiosis I involves:

– Synapsis – homologous chromosomes pair up. Chiasmata form (crossing over of non-sister chromatids).

– In Metaphase I, homologous pairs line up at metaphase plate.

– In Anaphase I, sister chromatids do NOT separate.– Overall, separation of homologous pairs of chromosomes,

rather than sister chromatids of individual chromosome.

Meiosis KM 42

Meiosis KM 43

Animation

Meiosis KM 44

Meiosis 1

First division of meiosis • Prophase 1: Each chromosome dupicates and

remains closely associated. These are called sister chromatids. Crossing-over can occur during the latter part of this stage.

• Metaphase 1: Homologous chromosomes align at the equatorial plate.

• Anaphase 1: Homologous pairs separate with sister chromatids remaining together.

• Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the homologous pair.

Meiosis KM 45

Meiosis IISecond division of meiosis: Gamete formation • Prophase 2: DNA does not replicate. • Metaphase 2: Chromosomes align at the

equatorial plate. • Anaphase 2: Centromeres divide and sister

chromatids migrate separately to each pole. • Telophase 2: Cell division is complete. Four

haploid daughter cells are obtained.

Meiosis KM 46

Mitosis vs. meiosis

Meiosis KM 47

Meiosis KM 48

Meiosis creates genetic variation

• During normal cell growth, mitosis produces daughter cells identical to parent cell (2n to 2n)

• Meiosis results in genetic variation by shuffling of maternal and paternal chromosomes and crossing over.

No daughter cells formed during meiosis are genetically identical to either mother or father

During sexual reproduction, fusion of the unique haploid gametes produces truly unique offspring.

Meiosis KM 49

In humans

e.g. 23 chromosomes in haploid2n = 46; n = 232n = 223 = ~ 8 million possible combinations!

Meiosis KM 50

Crossing overChiasmata – sites of crossing over, occur in synapsis. Exchange of genetic material between non-sister chromatids.

Crossing over produces recombinant chromosomes.

Meiosis KM 51

Sex is costly!• Large amounts of energy required to find a mate

and do the mating: specialized structures and behavior required

• Intimate contact provides route for infection by parasites (AIDS, syphillis, etc.)

• Genetic costs: in sex, we pass on only half of genes to offspring.

• Males are an expensive luxury - in most species they contribute little to rearing offspring.

Meiosis KM 52

But …• More genetic diversity: more potential for survival of

species when environmental conditions change. – Shuffling of genes in meiosis – Crossing-over in meiosis – Fertilization: combines genes from 2 separate individuals

• DNA back-up and repair. – Asexual organisms don't have back-up copies of genes,

sexual organisms have 2 sets of chromosomes and one can act as a back-up if the other is damaged.

– Sexual mechanisms, especially recombination, are used to repair damaged DNA - the undamaged chromosome acts as a template and eventually both chromosomes end up with the correct gene.

Levels of Organization

Remember, the human body is organized in several levels, from the simplest to the most complex. . .

Cells – the basic unit of life

Tissues – clusters of cells performing a similar function

Organs – made of tissues that perform one specific function

Organ Systems – groups of organs that perform a specific purpose in the human body

***The purpose of the 11 organ systems is for the human body to maintain homeostasis.

The 11 Human Body Systems

The 11 human body systems are as follows:

-- nervous system -- integumentary system

-- respiratory system -- digestive system

-- excretory system -- skeletal system

-- muscular system -- circulatory system

-- endocrine system -- reproductive system

-- lymphatic (immune) system

The Digestive SystemPurpose: to convert food particles into simpler micromolecules that can be absorbed into the bloodstream and used by the body

Major Organs and their Functions:

Mouth – to chew and grind up food

-- saliva also begins the chemical breakdown

Esophagus – pipe connecting mouth to stomach

Stomach – secretes an extraordinarily strong acid (pH = 2) that leads to breakdown of food

-- once the food is broken down in the stomach and mixed with digestive juices, it is called chyme

Pancreas – produces the hormone insulin that regulates blood sugar levels

-- also help neutralize stomach acid

Liver – produces bile, which breaks down fats in foods

Gallbladder – pouch-like organ that stores bile for future use

Small Intestine – after digestion is complete, the chyme enters the small intestine where it is absorbed into the bloodstream

-- the chyme is propelled along by folded surfaces called villi, on the intestine

Large Intestine – removes water from the chyme and gets the waste ready for excretion

The Excretory System

Purpose: to rid the body of wastes, including excess water and salts

Major Organs and Their Functions

Kidneys – the main organs of the excretory system

-- waste-laden blood enters the kidney and the kidney filters out urea, excess water and other waste products, which eventually travel out of the kidney as urine

-- eventually they travel through the ureter to the urinary bladder

Rectum – solid (food) waste travels out of the body through the rectum

Skin – sweat glands remove excess water and salts from the body

Lungs – expel the waste gas carbon dioxide

The Excretory System

The Respiratory SystemPurpose: to provide the body with a fresh supply of oxygen for cellular respiration and remove the waste product carbon dioxide

Major Organs and Their Functions

Nose – internal entry and exit point for air

Pharynx – serves as a passage way for both air and food at the back of the throat

Larynx – your “voicebox”, as air passes over your vocal chords, you speak

Trachea – the “windpipe”, or what connects your pharynx to your lungs

-- a piece of skin, called the epiglottis, covers the trachea when you swallow, preventing food from entering

Bronchi – the two large passageways that lead from the trachea to your lungs (one for each lung)

-- the bronchi are further subdivided into bronchioles

-- eventually, the further subdivisions lead to tiny air sacs called alveoli

-- alveoli are in clusters, like grapes

-- capillaries surrounding each alveolus is where the exchange of gases with the blood occurs

The diaphragm is the muscle that causes you to breath

-- hiccups are involuntary contractions of the diaphragm

Image of the Respiratory System

The Circulatory SystemPurpose: to deliver oxygenated blood to the various cells and organ systems in your body so they can undergo cellular respiration

Major Organs and Their Functions

Heart – the major muscle of the circulatory system

-- pumps blood through its four chambers (two ventricles and two atria)

-- pumps deoxygenated blood into the lungs, where it gets oxygenated, returned to the heart, and then pumped out through the aorta to the rest of the body

-- valve regulate the flow of blood between the chambers

Arteries – carry blood away from the heart and to the major organs of the body

Veins – carry blood back to the heart away from the major organs of the body

Capillaries – small blood vessels where gas exchange occurs

Blood – the cells that flow through the circulatory system

-- red blood cells contain hemoglobin, an iron-rich protein that carries oxygen

-- white blood cells function in the immune system

-- platelets help in blood clotting

Spleen – helps to filter out toxins in the blood

Image of the Circulatory System

The Nervous SystemPurpose: to coordinate the body’s response to changes in its internal and external environment

Major Organs and Their Functions

Brain – control center of the body, where all processes are relayed through

-- consists of cerebrum (controls though and senses) and cerebellum (controls motor functions)

Spinal Cord – sends instructions from the brain to the rest of the body and vice versa

-- any organism with a major nerve cord is classified as a chordate

Nerves – conduct impulses to muscle cells throughout the body

Diagram of a Nerve Cell

The Endocrine SystemPurpose: to control growth, development, metabolism and reproduction through the production and secretion of hormones

Major Organs

-- hypothalamus

-- pituitary gland

-- thyroid

-- parathyroid

-- adrenal glands

-- pancreas

-- testes

-- ovaries

The Skeletal SystemPurpose: to provide structure and support to the human body

Bones are where new blood cells are generated (in the marrow), and require the mineral calcium for strength

Major Bones of the Human Body

-- femur (thigh bone) -- humerus (upper arm)

-- radius and ulna (lower arm) -- cranium (skull)

-- sternum (breastbone) -- clavicle (shoulder blade)

-- fibula and tibia (calf) -- vertebrae (back)

-- scalpula (shoulder) -- pelvic bone

-- coccyx (tail bone) -- phalanges (fingers/toes)

The Muscular SystemPurpose: works with the skeletal and nervous system to produce movement, also helps to circulate blood through the human body

-- muscle cells are fibrous

-- muscle contractions can be voluntary or involuntary

Major Muscles in the Human Body

-- biceps -- triceps -- deltoids

-- glutes -- hamstrings

The Immune SystemPurpose: to remove infectious diseases and other pathogens from the human body

Major Organs and Their Functions

Skin – also called the integumentary system, the skin is the body’s first line of defense

White Blood Cells – recognize disease agents (antigens) and create antibodies to tag and remove these antigens

-- phagocytes are the white blood cell type that actually eats and destroys these antigens

Lymph Nodes – help restore fluid lost by the blood and return it to the circulatory system

Natural Selection & Artificial Selection

• Natural variation--differences among individuals of a species

• Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful.

Evolution by Natural Selection

• The Struggle for Existence-members of each species have to compete for food, shelter, other life necessities

• Survival of the Fittest-Some individuals better suited for the environment

Struggle For Existence & Survival of The Fittest

Natural Selection

• Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment

Descent

• Descent with Modification-Each living organism has descended, with changes from other species over time

• Common Descent- were derived from common ancestors

Evidence of Evolution

• The Fossil Record

• Geographic Distribution of Living Things

• Homologous Body Structures

• Similarities in Early Development

Evidence for Evolution

• The Fossil Record-Layer show change

• Geographic Distribution of Living Things

• Homologous Body Structures

• Similarities in Early Development

Evidence of Evolution• The Fossil Record• Geographic

Distribution of Living Things-similar environments have similar types of organisms

• Homologous Body Structures

• Similarities in Early Development

Homologous Structures

• Homologous Structures-structures that have different mature forms in different organisms, but develop from the same embryonic tissue

Evidence for Evolution

• Vestigial organs-organs that serve no useful function in an organism

• i.e.) appendix, miniature legs, arms

Similarities in Early Development

Summary of Darwin’s Theory

• Individuals in nature differ from one another

• Organisms in nature produce more offspring than can survive, and many of those who do not survive do not reproduce.

Summary of Darwin’s Theory

• Because more organisms are produce than can survive, each species must struggle for resources

• Each organism is unique, each has advantages and disadvantages in the struggle for existence

Summary (cont.)

• Individuals best suited for the environment survive and reproduce most successful

• Species change over time

Summary (cont.)

• Species alive today descended with modification from species that lived in the past

• All organisms on earth are united into a single family tree of life by common descent

Have you ever wondered how animals are able to survive in the

wild?

Animals have certain adaptations that help

them to survive.

Think about the way you dress in the winter.

You don’t wear your shorts and bathing suit when it’s snowing outside!

You wear warm clothes, and maybe even a hat and mittens to protect

yourself from the weather.

The way you dress in the winter, as well as the way that you run and hide from

someone throwing snow at you are kinds of …

Adaptations.

We can separate adaptations into two categories:

Physical

AND

Behavioral

A

D

A

P

T

A

T

I

O

N

S

Physical adaptations

are body structures that allow an animal to find and consume food, defend itself,

and to reproduce its species.

Physical adaptations help an animal survive in its environment.

Hey! I’m a walking stick. I look just like a stick you’d find on the ground.

© A. Weinberg

Physical adaptation

Camouflage (use of color in a surrounding)

The chameleon can change its color to match its surroundings. Can you do that?

Mimicry (looking or sounding like another living organism)

The Viceroy butterfly uses mimicry to look like the Monarch butterfly. Can you tell them apart?

Poisonous

Not poisonous

Physical adaptation

I’m the Monarch!

I’m the Viceroy!

Chemical defenses (like venom, ink, sprays)

Physical adaptation

Body coverings & parts (claws, beaks, feet, armor plates, skulls, teeth)

Physical adaptations

The elephant’s trunk is a physical adaptation that helps it to clean itself, eat, drink, and to pick things up.

Now let’s learn about

Behavioral Adaptations…

Behavioral Adaptations allow animals to respond to

life needs.

Each organism has unique methods of adapting to its environment by means of

different actions.

Behavioral Adaptations are animals’ actions.

Remember that Physical Adaptations are body

structures.

We can divide Behavioral Adaptations into two groups:

Instinctive Learned

These behaviors happen naturally & don’t have to

be learned.

These behaviors must be taught.

Instinctive behaviors happen

naturally & don’t need to

be learned

=

Finding shelter

Methods of gathering & storing food

Defending oneself

Raising young

Hibernating

Migrating

Learned behaviors

Obtained by interacting with the environment and cannot be

passed on to the next generation

except by teaching.

=

In this lesson, we have learned about animal adaptations.

There are 2 ways to describe adaptations:

Physical and Behavioral

Nevada's BioregionsWestern Nevada:Transition zone from Sierra Nevada bioregion to Great Basin cold desert.

Dominate plant species: Single Leaf Pinion, Rabbit Brush, Utah Juniper, Sage, Native Grasses.

Eastern Nevada: Great Basin bioregionDominate animal species:

Larger Mammals: Feral HorsesDescendants of domestic European horses that have become wildFeatured on the Nevada State quarterHerds are “managed” so that they don’t destroy fragile rangeland

BearsThis bioregion is home to the American Black BearLarge and adaptable omnivore

Mountain LionThe largest predator of the bioregion.

Great Basin BioregionCentral / Eastern Nevada Classified as a cold desertNot as dry as the Mojave Desert

Tall mountain ranges provide unique local climatesDominate plant species: Utah JuniperBerries are a food source for birds

SingleleafPinionUsed by Native Peoples and animals as a major food source

Great Basin Bristlecone PineBelieved to be the oldest living organism on earthCore samples of tree rings confirm 2500 years old

Two Secrets of Survival: Energy Flow and Matter Recycle

• An ecosystem survives by a combination of energy flow and matter recycling.

Figure 3-14

Fig. 3-26, p. 72

PrecipitationPrecipitation

Transpiration

Condensation

Evaporation

Ocean storage

Transpiration from plants

Precipitation to land

Groundwater movement (slow)

Evaporation from land Evaporation

from ocean Precipitation to ocean

Infiltration and Percolation

Rain clouds

RunoffSurface runoff

(rapid)

Surface runoff (rapid)

Fig. 3-27, pp. 72-73

Effects of Human Activities on Carbon Cycle

• We alter the carbon cycle by adding excess CO2 to the atmosphere through:– Burning fossil fuels.– Clearing vegetation

faster than it is replaced.

Figure 3-28