Cells

Big Ideas

Parts of the Cell• Cell Membrane- The membrane that surrounds the cell. Controls what goes

into and out of the cell • Ribosomes -The sites of protein synthesis. This is the “workbench” where

proteins are put together.

• Nucleus- Organelle that manages or controls all of the cell functions in a eukaryotic cell. “The control center, which contains DNA.”

• Chloroplast- Uses solar energy to convert carbon dioxide and water into glucose and oxygen. Site of photosynthesis.

• Mitochondria- Produces a usable form of energy (ATP) for the cell. Uses glucose, oxygen and water to make ATP, which cells use for energy.

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Outside of Cell

Inside of Cell

Cell Membrane Structure & FunctionHow will molecules move? (direction & route)

• Molecules moving across a cell membrane is called diffusion.

• Water moving across a cell membrane is called osmosis.

• Passive transport uses NO energy and Active transport uses energy.

Cell Membrane Structure & Function

Mitosis and Meiosis and Evolution

Big Ideas

Mitosis

• Mitosis: produces two IDENTICAL cells from one cell for growth and repair

Meiosis

• Meiosis: produces four UNIQUE sex cells for reproduction– Females: Eggs– Males: Sperm

• Sex cells have half the DNA in a UNIQUE combination• UNIQUE combinations allow for differences

(variation) in populations

Mitosis and Meiosis

DNA and Genetics

Big Ideas

DNA: deoxyribonucleic acid; is a code for your physical (phenotype) traits

- PHYSICAL TRAIT

DNA & Genetics

DNA Structure

• DNA is a Double Helix– “Twisted Ladder”

• The rungs of the ladder are made of 4 distinct nucleotides– G, C, A and T

Making Proteins

• Transcription– DNA is read to make RNA

• Translation– RNA is read to make a protein

• Proteins: can be used to make body structures, hormones and enzymes

– Enzymes act to speed up (catalyze) chemical reactions in the body

• Ex. Digestion of food, making DNA, and regulating glucose

Genetics Vocabulary

• Phenotype: What you physically look like• Ex. Blue Eyes OR Brown Eyes

• Genotype: What your genes are• Ex. Bb, bb, or BB

Vocabulary

• Dominant: Trait/gene that is shown• Ex. BB = Brown Eyes Bb = Brown Eyes

• Recessive: Trait/gene that is hidden by a dominant gene

• Ex. bb = Blue Eyes Bb = Brown Eyes

Vocabulary

• Heterozygous: different genes– Ex. Bb for Brown Eyes

• Homozygous: same genes– Ex. bb for Blue Eyes

• Punnett Square: used to predict offspring– Ex. Two heterozygous bunnies are crossed; black fur

is the dominant trait

– Phenotype ratio• Ex. 25% white bunnies, 75% black bunnies

– Genotype ratio• Ex. 25% bb, 50% Bb, 25% BB

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Earlobes (E) A detached earlobe man (EE) has children with an attached earlobe woman (ee). 1) What are the possible genotypes (gene

combination)?2) What are the possible phenotypes (physical

trait)?

Evolution

• Evolution: change over time

All living things are related to a

COMMON ANCESTOR!!!

Evidence of Evolution

Fossil Record Homologous Structures• Homologous and Vestigial

Structures• Presence of Fossils found in rock

layers

Evidence of Evolution

DNA Comparisons

Humans and mice are 99% similar in DNA, so they are closely relatedHumans and bananas are 55% similar in DNA, so they are NOT closely related

Embryos

Closely related organisms have similar embryos

Natural Selection

• Natural Selection: “survival of the fittest, failure of the worst”– The “goal” of life is to survive and reproduce– Based on ability to survive in environment

• Mutations in DNA: can (not always) lead to unique traits, which may help or hinder survival!!

Organism Environmental Pressure

Traits Which one survives?

What genes become more common in population?

Bunny Rabbits

Winter Brown Fur –or-White Fur

Giraffe Tall Trees Short Neck –or- Long Neck

Photosynthesis and Cellular Respiration

Big Ideas

Photosynthesis & Cellular Respiration

• Photosynthesis and cellular respiration are opposite chemical reactions

• Photosynthesis: plants take carbon dioxide (CO2) and water (H2O) and make glucose (C6H12O6) and oxygen (O2)

– Plants make their own food!!!!!!!!!!!!!!!!

• Cellular Respiration: plants AND animals make energy (ATP) by transforming glucose (C6H12O6)and oxygen (O2) into carbon dioxide (CO2) and water (H2O)

– CHEMICAL Energy in glucose is transformed into the energy to live (ATP)

– Very similar to setting something on fire (combustion), which releases carbon dioxide (CO2) into the atmosphere

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ATP

CO2

GLUCOSE

Balancing Biological Systems

Homeostasis

• Homeostasis: regulation of systems to maintain balance

• Two things can affect homeostasis– Negative Feedback– Positive Feedback

Negative Feedback

• Negative Feedback: increase causes decrease, decrease causes increase– Ex. Automatic Thermostat: if temperature

decreases in room, then the temperature increases

–Negative ≠ bad

• Positive Feedback: increase causes increase; decrease causes decrease– Ex. No shower for 2 weeks: smell from bacteria

growth increases on a daily basis

• Positive ≠ good

Positive Feedback

Negative or Positive Feedback??

Deforestation

Regulating Body Temperature (too hot OR cold)

Immune System Fighting Infection

Body is Hungry

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Ecology

Big Ideas

Energy vs. Nutrients

• Energy flows through every ecological system

– Inputs = what goes into the ecosystem

– Outputs = what goes out of the ecosystem

• Nutrients cycle through every ecological system

Food Webs

• Increased biodiversity = a healthier ecosystem

Energy Transfer between Trophic Levels

• 10% Energy Transfer• Producers make up largest biomass

Carbon Cycle

• Cycles carbon through the ecosystem• Contains photosynthesis and cellular respiration– Opposite chemical reactions

Nitrogen Cycle• Cycles nitrogen

through the system

• Bacteria takes nitrogen from the atmosphere and transfers it to plants

Population Growth

• Populations will grow exponentially if there are no limiting factors

• Examples of limiting factors are:– Food– Water– Shelter– Space

Population Growth

• Populations will reach carrying capacity because of limiting factors which include:– Abiotic (non-living)• Space & Water

– Biotic (living)• Food & Predators

Population Density

• Population Density is the number of living things in an area– Example:• 500 moose in 10 sq. miles = 50 moose per square mile

General Ecology

• Non-native species usually DIE in a new environment, some survive and take over if they have no predators

Sustainability

• Maintaining resources for future use

• Choices we can make now that support sustainability– Substituting renewable (?) for non-renewable (?)

resources– Recycling– Using fewer resources

Writing a Science Conclusion

1. Read the scenario– Write “things” or “stuff” above the words you don’t

know

2. Look at the data table3. Figure out the relationship between variables– Increase causes decrease OR decrease causes increase– Increase causes increase OR decrease causes decrease

4. Write conclusion based on DATA TABLE averages

Example Scenario• Scenario: Tom and Jane wanted to find out how

exposure to sunlight affected plant growth.

Sunlight Exposure (hours)

Plant Growth (cm)Trial 1 Trial 2 Trial 3 Average

2 hrs 1.5 2 1.5 24 hrs 2.5 3 3.5 36 hrs 4 6 5 58 hrs 10 8 6 8

Data:

Sunlight Exposure vs. Plant Growth

Example sentences for each conclusion bullet point

• “As sunlight increases, plant growth increases.”

• “8 hours of sunlight caused the greatest plant growth at 8cm and 2 hours of sunlight caused the least plant growth at 1cm.”

• “So the plant exposed to MOST sunlight grew 7cm MORE THAN the plant exposed to the least sunlight.”

• “The explanation for this is that plants need sunlight to go through photosynthesis to grow.”