Plant & Humans Test 2

Photosynthesis

Sunlight energy converted into chemical energy (food) by plants

Photosynthesis Formula

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

In the chloroplasts in the leaf cells

Where does photosynthesis happen?

Characteristics of Chloroplasts

Double membraned

Have chlorophyll & other pigments

Has thylakoids, granum, & stroma

Thylakoids

coin-shaped, sac shaped membranes inside the chloroplasts, inside the chloroplasts

Granum (“Grana” is plural)

One stack of thylakoids

Stroma

Ground material/fluid inside the chloroplasts with enzymes

Pigment

Substance that produces a color due to light absorption & reflection

Three kinds of pigments in chloroplasts

Chlorophyll A, Chlorophyll B, Carotenoids

Chlorophyll A

Primary pigment for photosynthesis

Three times as much as much as chlorophyll B

Absorbs in the red & blue areas of light spectrum

Chlorophyll B

Absorbs in the red-orange & blues areas in the light spectrum

Carotenoids

Cartonenes (orange) ex. carrots

Xanthophylls (yellow) ex. marrigolds

Absorbs in the green & violet areas of the light spectrum

Accessory pigments → help transfer absorbed light to chlorophylls

Acts as “sunscreen”

Stages of photosynthesis

1) Light-dependent / light reactions

2) Light-independent / calvin cycle

1) Light-dependent / light reactions

Occurs in the thylakoids

Light is required

Water molecules are split resulting in the release of Oxygen

Electrons release NADP+ to NADPH

Some ATP is formed

2) Light-independent / calvin cycle

Occurs in the stroma

Carbon dioxide is fixed and reduced to form sugars (ATP & NADPH from the light reactions are used)

Involves entry of carbon dioxide

Cellular Respiration

Breaking down the chemicals bonds in glucose through chemical reactions to produce cellular energy (ATP)

Oxidation of glucose → CO_2, H₂O, ATP

Cellular Respiration Formula

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Chemical Energy (in ATP)

Mitochondria

Where does most of cellular respiration happen?

Steps of Aerobic Cellular Respiration

1) Glycolysis

2) Citric Acid Cycle / Kerbs Cycle

3) Electron Transport Chain

Characteristics of mitrochondria

Has 2 membranes

Has a highly folded inner membrane (folds are known as cristae)

Has an inner membrane space (gap between the outer & inner membrane)

Has a matrix (innermost area within the mitochondria, contains enzymes & in enclosed by the inner membrane)

ATP

Cellular energy currency

Adenosine triphosphate

1) Glycolysis

Splitting of glucose

Occurs in the cytosol

Glucose splits into 2 pyruvate molecules

2) Citric Acid Cycle / Krebs Cycle

Happens in the matrix of mitochondria

Release of carbon dioxide

Requires oxygen

3) Electron Transport Chain

Happens in the inner mitochondrial membrane

Oxygen must be present

Produces most of the ATP

Types of Cellular Respiration

Aerobic and Anaerobic

Aerobic Cellular Respiration

Oxygen must be present

Anaerobic Cellular Respiration

Oxygen absent

2 types (alcoholic fermentation & lactic acid fermentation)

Alcoholic Fermentation

Some types of yeast, bread-making, beer-making, wine-making

Lactic Acid Fermentation

Some types of bacteria, muscle cells

1) Perception

External environment, interal plant body

2) Information Transfer

Hormones

3) Response

Action

Stimulus

Something that happens to cause an activity

Statocyte

Gravity-sensing cell in the root

Statolith

Starch grains inside the statocyte

Information Transfer

Which part of the stimulus/response process do hormones deal with?

Hormones

Chemical messengers

Made in small amounts but have large impacts

Plant Hormones

Auxin, Cytokinin, Abscisic Acid, Gibberellin, Ethylene

Auxin

Most important plant hormone

Used in apical dominance, cell suppression & elongation

Cytokinin

Auxin’s antagonist

Activated cell division

Dormant buds

Abscisic Acid

Involved in stress responses

Gibberellin

Seed germination

Ethylene

Fruit ripening

Steps of seed germination

1) embryo takes in water and swells

2) embryo produces gibberellin, and the gibberellin is moved to the aleurone layer; enzymes are produced

3) enzymes move into the endosperm

4) enzymes digest the endosperm to provide nutrients for the embryo

Plant responses

Tropic, mastic, morphogenic, all-or-none, dosage-dependent

Tropic Response

Growth associated with a stimulus; permanent

Positive (toward the stimulus)

Negative (away from the stimulus)

Diagonal growth

Nastic Response

Temporary

Non-growth response; not oriented to a stimulus

Morphogenic response

Changes in plant development or quality

All-or-None response

NO response happens unless a certain threshold is met

Venus flytrap

Dosage-dependent response

The dose determines the response

Etiolation

Differences in development when seedlings are grown in darkness

Characteristics of Etiolation

Long and stringy (internodes)

Apical hook

Beige/tan

Miniature, underdeveloped leaves

Phototropism

plants growing toward the light

oattips

Gravitropism

Roots bending downard toward gravity

Apical Dominance

Terminal bud makes auxin that shows the growth of other buds along the plant

Fruit Ripening Catagories

Climacteric and Non-climacteric friuts

Difference in Ethylene

Climacteric Friuts

MUCH ethylene is involved in ripening

CAN harvest early/ripened off the plant

Ex.: bananas, tomatoes, apples, avacados

Non-climacteric fruits

Little to NONE ethylene is involved in ripening

Can NOT harvest early/must stay on the plant to ripen

Ex.: cherries, grapes, oranges

Fruit ripening changes

color, taste, odor, firmess/texture, size

Types of reproduction

Asexual and sexual

Asexual Reproduction

Quicker

1 parent involved

No genetic diversity

Sexual Reproduction

There is genetic diversity

More time consumning/slower

2 parents involved

Vegatative propagation

Asexual reproduction in plants

Involves parent plant producing runners that form buds and roots

Ex.: spider plants, strawberries

Nucleus

Control center of the cell

Contains the DNA (genetic material)

Genetic material holds the instructions to make proteins

Chromatin

DNA and protein

DNA is neatly organized around protein to be able to fit inside

Chromosome

Formed when chromatin condenses

Duplicated chromosome

“Pair of sister chromatids”

Identical copies

Diploid

Symbol: 2n

Two complete sets of chromosomes

Human’s body cells 2n=46

Haploid

Symbol: n

1 complete set of chromosomes

Human’s sex cells n=23

Cell Cycle

Life cycle of a cell from one division to the next

Cell cycle phases

1) Interphase

2) Cell/Nuclear Division

3) Cytokinnesis

Interphase

First part of cell cycle

Cells spend most time here

DNA in chromatin form

G1, S, G2 (3 phases)

G1 Phase

cell growth

enzymes and other proteins made

increase in number and size of organelles

S (synthesis) Phase

DNA is copied

G2 Phase

proteins are made

final preparations before division

Cell / Nuclear Division

Second part of cell cycle

Cells spend some time in

Divisin of nucleus (DNA)

Mitosis or meiosis

Cytokinesis

Third part of cell cycle

Cells spend the least amount of time here

Separate nuclei into separate cells

Phragmoplast builds up across the dividing cell to form a cell plate, which separates the newly formed daughter cells (plants)

Which part of the cell cylce includes mitosis/meiosis?

Cell/Nuclear Division

Mitosis

Happens in body cells

Associated with asexual reproduction (producing clones)

PMAT (Prophase, Metaphase, Anaphase, Telophase)

Prophase

1) Chromatin condenses so duplicated chromosomes/pairs of sister chromatins are seen

2) The nuclear envelope and nucleolus break down

3) The spindle, which is made of microtubles, begins to form

Metaphase

1) Duplicated chromosomes/pairs of sister chromatids attach to the spindle and line up in the middle of the cell

Anaphase

1) Duplicated chromosomes/pairs of sister chromatids are pulled apart. They are called chromosmes.

Telophase

1) The chromosomes unravel back into chroamtin

2) The spindle brekas down

3) The nuclear envelopes and nuclei reform

Cytokinesis

Forms 2 separate, indentical daughter cells

Meiosis

Happens in reproductive cells

Decrease the amount of DNA by half

Associated with sexual reproduction

Meiosis 1 and Meiosis 2 (go through PMAT twice)

At the end of both parts (1&2), 4 nuclei have been produced

Meiosis 1

Separate homologous chromosomes

Homologous Chromosomes

Pair of chromosomes with genes for same traits, same size and shape

Meiosis 2

Separate chromatids

Meiosis 1 Process

Prophase 1

Metaphase 1

Anaphase 1

Telopahse 1

Prophase 1

Nuclear envelope and nucleolus break down

The spindle begins to form

Chromatin condenses (homologous chromosomes can be seen)

Homologous chromosomes pair (synopsis)

Crossing over occurs

Crossing over is what, and happens during what phase?

Exchange of information between homologous chromosomes, happens in Prophase 1

Metaphase 1

Homologous chromosomes attach to the spindle and line up in the middle of the cell

Anaphase 1

Homologous chromosomes are separated

The amount of DNA has decreased by half

Telophase 1

The spindle breaks down

DNA unravels into chromatin

The nuclear envelopes and nuclei reform

Cytokinesis 1

Its own separate step

2 daughter cells with half the amount of DNA as the original cell

Meiosis 2

No interphase before

Prophase 2

Metaphase 2

Anaphase 2

Telophase 2

Prophase 2

The spindle begins to form

DNA condenses so chromatids can be seen

The nuclear envleops and nuclei break down

Metaphase 2

The DNA attaches to the spindle and lines up in the middle of the cells

Anaphase 2

The DNA (chromatids) separate and are called chromosomes

Telophase 2

The spindle breaks down

DNA (chromosomes) unravels back into chromatin

The nuclear envelopes and nucleoi reform