Biology and Society Unit 3 Exam

Originating in human activity

Process used by plants and certain microbes to trap light energy

Organelles where photosynthesis occurs

Inner and outer membranes

Thick fluid in chloroplast holding enzymes for photosynthesis

Disk-like membranous structures; stacked in piles

• Pigment that covers the surface of thylakoid membranes -Absorbs light energy in blue and red wavelengths

• Reflects green wavelengths

General Equation: Carbon Dioxide + Water + Light Energy -> Glucose + Oxygen Chemical Equation: 6CO2 + 6H2O -> C6H12O6 + 6O2

• The Light Reactions

• The Light-Independent Reactions

• Series of reactions occurring on and in thylakoid

• Require sunlight

• Produce oxygen, ATP, and NADPH

• Uses electron transport chain to produce the ATP, like mitochondria

1. Sunlight excites chlorophyll, removing electrons and H+ from water

2. Electrons pump H+ into thylakoid via the electron transport chain

3. H+ exits thylakoid through ATP synthase, making ATP

4. H+ and electrons combine with NADP+ to make NADPH

5. NADPH and ATP are products of the light reactions

• Series of reactions occurring in the stroma

• Does NOT require light

• Uses ATP and NADPH from light reactions, and CO2 from the atmosphere

• Creates G3P (a 3-carbon molecule) which is used by the cell to make sugars and carbs

• Uses enzyme rubisco, the most abundant enzyme on the planet

1. Sunlight and H2O enter thylakoid

2. Light reactions yield ATP, NADPH, and O2

3. ATP, NADPH, and CO2 enter stroma

4. Light independent reactions yield 3-carbon molecules

5. Cell uses 3-carbon molecules to make sugars

Openings in leaves for entrance of gases

Regulate stomata openings

Movement of water through stomata

• Transpiration occurs

• Gas exchange occurs; carbon dioxide enters, oxygen exits

• No transpiration

• No gas exchange

Series of reactions that counteract photosynthesis

• C3

• C4

• CAM

• Includes most plants and trees

• Close stomata to conserve water when hot

• Photorespiration may occur

• Mechanism to reduce photorespiration

• Many grasses are C4 plants

• Additional pathways concentrate carbon dioxide to produce four-carbon sugars, even when stomata are barely open or closed

• Lower rates of photosynthesis (and removal of atmospheric carbon dioxide) compared to C3 plants

• Mechanism to reduce photorespiration

• Include cacti and succulents

• Open their stomata only at night

• Store carbon dioxide as an organic acid

• Acid is broken down during the day for photosynthesis

• Lower rates of photosynthesis (and removal of atmospheric carbon dioxide) compared to C3 plants

• Adapted to temperate and cooler, moister environments (where they can keep stomata wide open)

• Less efficient (more photorespiration) in warmer, dryer environments

• Adaptations for losing less water during photosynthesis (having stomata barely open or closed part of the time)

• Not as efficient in temperate and cool environments compared to C3

• More efficient (less photorespiration) in warmer, dryer environments

• (loss of trees) can lead to reduced photosynthesis

• Clearing of forests for logging, farming, and human settlements

• C4 grassy plants outperform C3 trees in warm temperatures = more likely to take over as earth warms

• But trees capture more carbon than grasses

• 25% of carbon dioxide added to the atmosphere comes from cutting and burning forests in the tropics

• Reforestation projects promote photosynthesis and reduce deforestation effects

• Conversion of vegetated land to desert

• Fewer plants and less carbon dioxide uptake

• Pro: more plants and carbon dioxide uptake

• Cons: -Enhanced carbon dioxide released from more decay of carbohydrates in soil -Increased heat gain- darker surface absorbs more light energy

Local changes in average climate conditions occurring all over the planet

The progressive increase of Earth's average temperature over the last century

Human-caused global warming

Gases that absorb and emit thermal infrared energy

• Water vapor

• Carbon dioxide

• Methane

• Ozone

Atmospheric greenhouse gases trap energy from the sun

1. Sun shines on the Earth's surface (broad spectrum of radiation

2. Earth gives off this energy in heat (infrared radiation)

3. Some heat warms greenhouse gases in the atmosphere, and some escape into space

4. Heat absorbed by greenhouse gas is re-radiated in all directions

5. This heat is either absorbed by other greenhouse gas molecules, absorbed by the Earth, or it is radiated into space

• More greenhouse gases in our atmosphere= More heat trapped on Earth

• Greenhouse gases act like an atmospheric blanket

• Sleeping under a blanket

• Your body heat warms the blanket

• The blanket re-radiates some of that heat back to you, keeping you warm

• Increased greenhouse gases

• Thicker blanket

• More heat retained and re-radiated

• Warmer temperature under blanket

• An insulating blanket of gases including water vapor and carbon dioxide surrounding Earth

• Prevents sun's heat from escaping into space during the night

• Makes Earth habitable

Attraction between neighboring water molecules

The total amount of energy associated with movement of atoms and molecules

Measures the intensity of heat; how fast molecules move

• Large volumes contain more heat due to greater totals of molecular movements

Carbon flows between:

• Living organisms

• The atmosphere

• Bodies of water

• Rock

Highly concentrated energy source

• Produced from unconsumed carbohydrates of ancient, buried organisms (mostly plants and microbes)

• Transformed by heat and pressure

Sections of DNA with instructions for building cell proteins

• A basic unit of heredity

• Control traits such as eye color

Made of DNA wired around proteins

• In uncondensed string-like form before cell division

• Compressed into a compact linear structure for cell division

• Each carries hundreds of thousands of genes

Copied chromosomes with the same genes

• Attached at the centromere

• Occurs before cell division

• Begins by splitting the helix in half (up the middle)

• Newly formed DNA strand

• One half new daughter DNA

• One half conserved parental DNA

An enzyme that assists DNA replication

• Moves along the unwound DNA

• Facilitates synthesis of the new strand

• Catalyzes the formation of covalent bonds between adjacent nucleotides

Asexual cell division produces two daughter cells that are identical to each other and the parent cell (occurs in somatic cells)

Body cells not involved in sex cell production (most of the cells in the human body)

Tube-shaped protein structures, that provide structure and shape to eukaryotic cells; used for movement of chromosomes in mitosis

Cylindrical organelle made of protein, involved in arranging microtubules

Opposite ends of a dividing cell

Membrane surrounding the nucleus; is a phospholipid bilayer, like most membranes

Region (composed of a DNA sequence) that links a pair of sister chromatids

1. Interphase(DNA replication)

2. Mitosis(copied chromosomes are moved into daughter nuclei)

3. Cytokinesis(parental cell cytoplasm splits into two daughter cells

Normal cells are most often in this step of the cell cycle Has three phases:

1. G1 (first gap or growth): organelles duplicate; cell grows

2. S (synthesis): chromosomal DNA replicates

3. G2 (second gap): cell grows and prepares for mitosis

Prophase--> Please Metaphase--> Make Anaphase--> Another Telophase--> Tiny Cytokinesis--> Cell

DNA has replicated but it has not yet condensed into chromosomes

Chromosomes condense (into sister chromatids) Microtubules form and grow Attached motor proteins pull chromosomes around Animal cells: microtubules attached to centrioles at the poles of the cell Plant cells: microtubules are present, but not centrioles Nuclear envelope breaks down

Chromosomes (sister chromatids) alight across the middle of the cell, moved by microtubules

Centromers split Microtubules shorten to pull each sister chromatid to opposite poles

Nuclear envelopes reform around chromosomes in nuclei Chromosomes revert to uncondensed form

division of the cytoplasm Is NOT a stage of mitosis Occurs after telophase of mitosis Cell is split into two daughter cells Cells then reenter interphase Cells can divide again under favorable conditions

Band of proteins encircles cell at equator Proteins contract (like tightening a belt) and pinch apart the original cell into two daughter cells

Vesicles deliver materials for cell wall: inflexible structure surrounding plant cells Cellulose- fibrous carbohydrate Proteins Vesicle membranes form a cell plate Cell plate and new cell wall grows as a barrier across the cell width

Prokaryotes (bacteria and archaea) do NOT perform mitosis! They perform binary fission (division of a single entity into two parts), a form of asexual reproduction Most bacteria have DNA in one circular chromosome DNA is uncoiled and duplicated (#2) DNA is pulled to separate poles and cell increases size (#3) New cell wall divides two cells (#4-6)

production of gametes (genesis=production)

specialized male and female reproductive cells (sperm and egg) Begins with meiosis: specialized cell division in sexually-reproducing organisms used to make gametes Continues with further maturation modifications Sperm cells add tail and increase mitochondria Egg cells increase in size and nutrient concentration

specialized form of cell division to produce gametes Occurs only in gonads (sex organs) Testes in males Ovaries in females Reduces number of chromosomes by half Human somatic (body) cells have 46 chromosomes Human gametes have 23 chromosomes

Found in somatic cells One chromosome from the mother and one from the father Same size Same shape Carry the same genes May have different alleles : different versions of a gene Example: different alleles result in different eye colors

Displayed in magnified photograph arranged in 23 pairs by size Each pair= homologous 22 pairs of autosomes: nonsex chromosomes 1 pair of sex chromosomes XX for females XY for males

exchange of genetic information between homologous chromosomes Creates new combinations of alleles on a chromosome Gametes can contain individual chromosomes with genetic information from both parents

members of homologous pairs are arbitrarily arranged to face a pole Resulting in genetically diverse gametes Over 8 million possible alignments from 23 pairs of chromosomes

type of cell division One parent cell divides into two genetically identical daughter cells Regulated to occur only when more cells are needed Development and growth Cell replacement (dead/worn-out cells) Regeneration (replacing body parts) Asexual reproduction

a disease that occurs when cells replicate when they shouldn't Results when cell division regulation fails

a solid mass of cells with no apparent function

doesn't affect surrounding tissues

Invades surrounding tissues; cancerous

Malignant cells break away and start new cancers at distant locations

Fluid-filled lump with no function; not cancerous

Behaviors or conditions that increase the chance of developing a disease

Enhance the activity of other carcinogens

Cancer-causing agents

Sites of cell division regulation

Changes in the DNA of a gene

Proteins that regulate cell division

Mutations may lead to tumor formation

-Few are inherited

• Most occur with exposures to environmental risk factors

Surgical removal of cells for microscopic analysis

The outer edge of the removed tissue

• Clear (negative)- cancer cells are not invading other tissue

• Not clear (positive)- cancer cells are found throughout -More tests may be required

• chemotherapy

• radiation therapy

• immunotherapy

chemicals that selectively kill dividing cells Used for cancers difficult to remove surgically or spreading to new locations Target-specific cell cycle events Injected into the bloodstream BUT normal cells that divide rapidly are also damaged Hair follicles Cells producing red and white blood cells Cells lining the intestines and stomach

use of high-energy particles (gamma radiation) to destroy cancer cells Used after surgical removal of the tumor or if surgery is not possible Usually cancers close to the surface Damages DNA of cancer cells BUT internal organs may be damaged by imprecise radiation beams

immune system selectively destroys cancer cells Targets cancer cells with specific surface marker proteins Healthy cells without those marker proteins are spread Less severe effect on patient health than chemotherapy or radiation May also be used to prevent cancer development HPV vaccine boosts immune system response

growth and reproduction of an individual Gametes (sperm and egg) fuse during fertilization to form a single-celled zygote Continued cell divisions form the embryo The embryo grows to become a fetus A full-term infant is born with continued growth and becomes an adult

Different versions of genes (produced by mutations)

Pairs of alleles separate into different gametes

Homologous pairs separate into gametes, randomly and independently of other chromosomes

Random chance of individual sperm fertilizing the individual egg (gametes combine regardless of alleles carried)

observable characteristics of an individual