Living Environment Regents Review

Cells are the smallest units of life.

Organelles are the structures inside the cell.

Nucleus- Contains DNA (genetic information) that controls the production of proteins

Ribosomes- Read the message sent from DNA and places AA in the correct order to form a protein. (order of AA determines SHAPE and Function of the protein)

Mitochondria- Site of Cellular Aerobic Respiration; makes ATP other metabolic activities needed to stay alive

Vacuoles- Store food (food vacuoles) or wastes

Cytoplasm- fluid (mostly water) where many chemical reactions take place.

Cell Membrane-controls what goes in (nutrients and 02 )or out (CO2 and wastes) of the cell.

Selectively permeable- only certain substances can pass through the membrane.

Diffusion- molecules move from a high concentration to a low concentration with no energy required. Osmosis is the diffusion of water.

Active Transport -molecules move from a low concentration to a high concentration ENERGY is

REQUIRED. The energy used by cells is ATP.

Receptor Molecules- on the cell membrane; the shape determines what substances it can attach to and bring into the cell.

Plant Cells have all of this Plus....

Chloroplasts- Site of Photosynthesis

• contains a green pigment called Chlorophyll

Vacuole- Store water and sugar

Life Functions:

1. Nutrition- nutrients are needed for energy (ATP), repair and growth.

1. Autotrophic Organisms- take in inorganic molecules (CO2 and H20) to from complex organic compounds (like glucose C6 H12 06) Ex.) Plants/Producers do photosynthesis

2. Heterotrophic Organisms- cannot make their own food and rely on other organisms for food

• Carbohydrates → simple sugars (glucose is an example)

• Proteins → amino acids

• Lipids → fatty acids and glycerol

• Nucleic Acids → nucleotides

1. Transport -materials must be distributed throughout the cell or body (nutrients, wastes, hormones, oxygen, antibodies...).

2. Respiration - Energy (ATP) is released from the bonds of glucose; happens in the mitochondria of the cells

3. Metabolism- all chemical reactions in an organism. Synthesis is the process of making materials in the body such as using nutrients to make proteins needed by the organism.

4. Regulation and Coordination- to maintain Homeostasis cells must be able to communicate (coordinate actions).

Homeostasis is the internal stability that all organisms maintain. Biochemical processes occur in living things and are essential for their survival.

PHOTOSYNTHESIS: Equation in words: Water + Carbon Dioxide Glucose + Oxygen Equation in chemical symbols: H20 + CO2 → C6H1206 + 02

• Happens in the chloroplasts of plant cells (chlorophyll is the pigment needed)

• Light energy from the sun is converted into chemical energy

Stomates- holes on the bottoms of leaves that open and close

CELLULAR RESPIRATION: Equation in words: Glucose + Oxygen Water + Carbon Dioxide + ATP Equation in chemical symbols: C6H1206 + 02 → H20 + CO2 + ATP

• Happens in the mitochondria of all cells

• Chemical energy from glucose is converted into ATP which is a form of energy used by cells

Organism - All systems working together to maintain life and homeostasis

All Systems in the Human Body:

• Digestive system - digest and absorb nutrients

• Respiratory System - Gas exchange (oxygen & carbon dioxide)

• Immune system - protects the body from viruses and bacteria (pathogens/antigens)

  • Pathogens- disease causing organisms (virus, bacteria, fungus, microorganisms, protists)

  • Antigens are like protein name tags that have a special shape the white blood cells can recognize the name tags to

  • White Blood Cells- produce antibodies that have a special shape to fit into or recognize the bad pathogens/antigens and destroy them or label them for destruction. (immune response).

  • Vaccines- dead or weakened pathogen injected into your body so the WBC can
    "practice" making antibodies for it...makes a person IMMUNE to the pathogen.

  • Antibiotics- medications given to fight bacterial infections.

  • Allergy-body makes antibodies to harmless antigens (pollen, dust, peanut butter)

  • AIDS- H.I.V. destroys WBC...no immunity

• Nervous system - used for fast communication between cells to maintain homeostasis

• Endocrine System - Hormones (chemical message) is sent through the blood to target cell/organ that has the correct shaped receptors

  • Feedback Mechanisms - maintain homeostasis by regulating the amount of sugar, water, calcium in your body/blood

  • Ex. If blood sugar is too high, insulin is released from the pancreas to bring it back to normal levels.

• Excretory System - removes wastes from the body (kidneys, skin, lungs)

• Skeletal/muscular system - locomotion

Dynamic Equilibrium- the constant small corrections that must occur to maintain homeostasis

Enzymes -Specially shaped proteins that digest or synthesize large molecules. They are needed for most metabolic activities (homeostasis/equilibrium).

• They are specific in their action and their substrate (what they digest or synthesize).

• Substrate "fits" into the enzyme

• Ex: protease digests proteins, lactase digests lactose, lipase digests lipids

• Enzymes are catalysts (increase the rate of the reaction)

• Ex. Starch will eventually breakdown into simple sugars but… Enzymes make the reaction happen 1000 times faster

• If you change the shape of an enzyme (denature), you change the speed of it or make it stop functioning

Factors Affecting Enzyme Activity:

• Temperature

• pH

• amount of enzyme or substrate

DNA (deoxyribonucleic acid) is found in the nucleus and stays there:

• carries the instructions for making proteins (put amino acids together in the correct sequence)

• has 4 different bases A, T, C, G

• has 2 strands(side by side) each base pairs with a complement (A=T and C=G)

• replicates before the cell divides (mitosis and meiosis) by untwisting and unzipping then copying each strand.

• Instructions are expressed in a code of three bases, on one strand, representing 1 of 20 different amino acids. (that is why proteins need the correct order to work)
  Ex.) T-A-C codes for Methionine

Since DNA stays in the nucleus, but the protein is assembled at the ribosome, DNA must copy its instructions (Base Sequence) onto a messenger that can leave the nucleus (mRNA)

Protein Synthesis:

• mRNA takes the code from DNA out of the nucleus

• at the ribosome tRNA with its attached amino acid pairs up with the mRNA

• The amino acids bond and break free of the tRNA

• The amino acid chain is now called a protein (or a polypeptide)

Genes - DNA's sequence of bases that code for a protein. Chromosomes have 1000's of genes on them and chromosomes are made of DNA

• can be turned on (expressed) or off (not expressed) depending on the cell’s environment

  • Ex: hormones turn cells on/off

• Cells specialize/differentiate because some genes are turned on or off

Mutation- Error in the DNA Sequence (inserting an extra base or deleting one) that causes a mistake in the order of amino acids in a protein (wrong shape = not work correctly)

• can be caused by chemicals or radiation

• can only be passed on to a baby if it occurs in the gametes

• may cause cancer

• cause genetic variation and may be good or bad changes

Selective Breeding- humans choosing organisms to mate in order to get the desired traits in offspring.

Recombinant DNA can be made by cutting DNA using special enzymes (restriction enzymes) and inserting genes into another organism's DNA.

• If an organism has the gene inserted into it, they can make the product

• Ex: Human insulin gene is pasted into a bacteria, bacteria can now make human insulin

Gel electrophoresis - fragments of DNA can be separated by size (small ones go through the gel faster than the larger ones)

Asexual Reproduction- one organism divides into two or more offspring

• Offspring are genetically identical to the parent

• Mitotic cell division (mitosis) is used to produce identical cells. A clone is genetically identical to the parent organism.

• Unicellular organisms (single celled) divide by mitosis to produce two identical cells.

*Multi-cellular organisms-mitotic cell division produces a mass of cells or replaces/regenerates lost cells that later bud off to form the offspring)

Steps in mitosis:

1. Chromosomes and genes are copied (DNA Replicated)

2. Each copy goes into a new cell

3. Every cell has the same chromosomes as the original cell

*No Variation within the population

-Can't adapt to changes that happen in the environment (there may not be any survivors if the environment contains a factor that the original parent is not adapted to)

Ex: No natural Selection/Evolution of population

*Fitness/High Adaptive Value/the genes that allow it to survive- are passed on to the next generation

Ex: Resistance genes(antibiotics, pesticides...) passes to the offspring

Sexual Reproduction- Two organisms donate 50% of their genes/DNA to form a new individual.

• Meiotic cell division(meiosis) produces sex cells - makes a cell with only half the DNA/Chromosomes/Genes as the original cell

• Gametes (sex cells/Sperm/Egg) transfer half of the genetic materials/DNA/Chromosomes.

• Fertilization- fusion of two gametes to form the zygote cell, maintaining the correct chromosome number from one generation to the next.

1. New offspring is a combination of the genes from the parents (not identical to them)

2. Increases variation (genetic differences)- new offspring may inherit Fitness/High Adaptive Value/the genes that allow it to survive....From both of parents

EX. Inherits resistance from mom or dad or both....but, there's no guarantee that genes with high adaptive value will be inherited

Human Reproduction- regulated by hormones (estrogen & testosterone are two examples)

Female Structures:

1. Ovary-produces egg (released during ovulation) and secretes hormones (estrogen and progesterone to regulate the cycle)

2. Oviduct/Fallopian tube- connects ovary area to uterus; where fertilization happens

3. Uterus- protects fetus (where baby develops/grows)

   1. Placenta- a temporary organ that provides nutrients, gas exchange and waste removal for the baby/fetus. Anything (good or bad) that is dissolved in the mother's blood will diffuse into the baby's blood through the placenta.

   2. Umbilical cord- carries baby blood to the placenta then back to baby

4. Cervix- the bottom of the uterus which opens into the vagina.

5. Vagina- also called the birth canal

Male Structures:

1. Testis- Produces sperm and provides hormone (testosterone) for male traits (beard, voice, muscle mass)

2. Epididymis- where sperm mature

3. Vas deferens- carry sperm from testis/epididymis to urethra; "snipped" in a vasectomy

4. Semen- mixture of sperm and fluids. Fluid is needed for sperm to swim.

5. Urethra- passageway leading out of the body for semen & urine

Embryonic Development:

• Mitosis- every cell has identical DNA/Chromosome/Genes

• Differentiation- cells become different/specialize depending on what genes are turned on or off. (Ex. nerve cell, skin cell, liver cell...)

• Environmental factors (hormones, cell location) can influence how genes are turned "on" or "off")

• If the mother is exposed to chemicals or drugs or disease during early pregnancy, the embryo development may be affected in a negative way. Ex.) Alcohol effects brain development

• Embryonic Development (remember..this is cell division by mitosis)

Evolution- change over time; change in the frequency (how often they appear) of selected genes within a population of organisms.

• organisms tend to become more complex as organisms evolve (change) through time

• genes that have high adaptive value (allow an organism to survive) will increase in number as time goes on (from one generation to another)

• Evolution(change) happens faster if the environment is changing

• Evolution (change) occurs as a result of Natural Selection

Natural Selection- Theory proposed by Charles Darwin in 1859

• if an organism has the genes that let them survive (have Adaptive Value), then they reproduce passing the genes on to the next generation then gene becomes more common in the population.

• in a changing environment, favorable genes accumulate rapidly changing the appearance or behaviors of the population.

• If a species doesn't adapt/evolve in a changing environment, they may go extinct

Four Steps of Natural Selection:

1. Overproduction- too many offspring are created (not all can survive because of limited resources in the environment)

2. Competition- because the species share common niches they will compete for food, space, mates...

3. Variation- Sexual reproduction (creates new combination of genes) Mutations change the DNA/gene slightly. Individuals in the population are not all the same. They contain different genetic information because of sexual reproduction and mutations.

4. Selection and Reproduction- the genes that are not adapted to the environment are selected against

• Genes that have an adaptive value will survive and be passed on to the offspring.

• If a population lacks genetic variation (asexual reproduction, no mutation, inbreeding), they lose the ability to adapt (evolve) to a changing environment.

• If two species share a common ancestry (they are related), they will have similar DNA, proteins, embryonic development, bone structures.

Biosphere- areas on earth where we can find life

Species- interbreeding population of organisms

Community- all the different populations in the ecosystem

Ecology- the study of the interaction between the living and nonliving things

Ecosystem- the interaction between living (biotic) and nonliving (abiotic) in a given area.

• Abiotic factors influence what types of organisms can live in the habitat. Ex.)Temperature in Florida vs. Alaska; Amount of sunlight at the top of a lake Vs the bottom

• Biotic factors help recycle abiotic materials Ex.) Aerobic Respiration Breaks C6 H12 06 down for ATP and releases the carbon dioxide (CO2) and water (H20)

To Remain Stable (self sustaining) Ecosystems must have:

1. Constant Source of Energy. (Sun or Chemicals)

2. Organisms that can convert the energy into a usable form. Then pass that energy on to others. Autotrophs (plants) use sunlight and CO, to make sugar (organic). Heterotrophs (animals) consume that sugar for energy (respiration).

3. Diversity- Many different producers and consumers. If one plant species dies then another can pick up the slack.

4. Recycle Materials- organisms must break dead things down so the nutrients in them can be used again. Bacteria and Fungi decompose dead producers and consumers down to release nitrogen. The nitrogen is then used by other plants to grow.

Food chain: producer → primary consumer → secondary consumer

Food Web: many food chains that are interconnected

Energy Pyramid: When a consumer eats another organism, the Energy is passed from one organism to the next.

90% of the energy is lost to metabolic activities

Ex. You have to find the food (lose energy), you have to ingest and digest the food (lose energy), you have to transport the food to the cells (lose energy) you have to convert the food to ATP (lose energy)

• since energy is lost every time it's transferred from one consumer to the next, the amount of organisms decreases at each level.

• Producers are always the foundation of the food/energy pyramid

photosynthesis: use sun energy to put COz and H20 (inorganic materials) together to make

C6 H2 06 (sugar/glucose/carbs) (organic compound)

Every organism has a job (niche) in the habitat (environment occupied)

Decomposers - break down dead plants and animals

Producers/Autotrophs - plants; can do photosynthesis to make food

Consumers/Heterotrophs - cannot make their own food; rely on other organisms for food

Herbivores - eat only plants

Carnivores- eat only other consumers

Scavengers- eat dead consumers

Predator- hunt and eat prey

Prey- try to escape the predator

Parasite- steals nutrients from a host

Host- what parasite steals from

Ecological Succession- Ecosystems Change / evolve. Plants and animals change the environment then the new environment attracts new plants and animal