Cellular Respiration, Photosynthesis, and lab...
Transcript of Cellular Respiration, Photosynthesis, and lab...
Cellular Respiration, Photosynthesis, and lab 4
4/20/16
Announcements
• We will not be covering chapter 9: cell communication
• Today, we will finish cell respiration (ch7), photosynthesis (ch 8), and start on cell division (ch 10)
• Lab is on cell division
• Also, must prepare seeds for next lab
Cellular Respiration – oxygen present
Cellular respiration
• Glycolysis
• Kreb’s or citric acid cycle
• Electron Transport Chain
• Overall reaction:
C6H12O6 + 6 O2 6 CO2 + 6 H2O + 38 ATP + heat
Energy carriers and electron carriers
• ATP – the main energy carrier molecule
• NADH, FADH2, and NADPH – electron carriers
GTP
The energy carrier molecule, ATP
• Three phosphate groups
• Ribose sugar
• Adenine base
Glycolysis
• Happens in cytoplasm• Convert glucose to 2 pyruvate or pyruvic acid• What are the reactants? What are the
products?
Glycolysis
• Reactants: Glucose, 2 ATP, 2 NAD+, and 4 ADP• Products: 2 pyruvate, 2 ADP, 2 NADH, 4 ATP, and H2O• Gained 2 ATP and 2 NADH
• Red blood cells get their energy here
Kreb’s or citric acid cycle
• Happens in the matrix of the mitochondria
• Citric acid is first product
• Closed loop
• What are the reactants? What are the products?
ATP
Kreb’s or citric acid cycle
• Reactants: 2 pyruvate, 8 NAD+, 2 FAD+, and 2 ADP
• Products: 6CO2, 2 ATP, 8 NADH, and 2 FADH2
• Gained 2 ATP, 8 NADH, and 2 FADH2
• Glucose catabolism complete
• So far, total of 4 ATP, 10 NADH, and 2 FADH2
ATP
Electron Transport Chain
• Only step that uses oxygen
• Relay race of e-
• Many in the inner membrane
• Oxygen and H H2O
• Leads to oxidative
phosphorylation –
Generating ATP using
chemiosmosis in
mitochondria
If there is no oxygen,
• Anaerobic bacteria, muscles, yeast
PHOTOSYNTHESIS
Energy
• Required to drive all chemical reactions that
sustain life
• Cannot be created or destroyed, so living things
must obtain it from the environment (1st law of
thermodynamics)
Trapping sunlight
• Ultimately, all living things on Earth derive energy from the sun
• Some directly by photosynthesis
– Photoautotrophs
• Others indirectly through the food chain
– Heterotrophs
Photosynthesis
• Takes place mostly in the leaves
• Why are leaves large and flat?
• They have specialized structures that allow all required components to come together
– H2O
– CO2
– Sunlight
Leaves
cuticle
upperepidermis
lowerepidermis
mesophyllcells
chloroplasts
outer membrane
inner membrane
thylakoid
stroma
stoma
stoma
bundle sheath cells
vascular bundle (vein)
channelinterconnectingthylakoids
Internal leaf structure
Mesophyll cell containing chloroplasts
Chloroplast
Leaf structure and photosynthesis
• Source of H2O: taken in through roots
• Problem: large surface area
• Solution: cuticle and stomata
– Waxy protective coating reduces water loss
– Stomata can open and close
Leaf structure and photosynthesis
• Source of CO2: air
• Problem: cuticle keeps gases out
• Solution: stomata
– Adjustable pores allow gases in (and out)
– Where the plant “breathes”
Leaf structure and photosynthesis
• Sunlight captured by chloroplasts
• Primarily in mesophyll layer of leaf
• One cell may contain 40-50 chloroplasts
cuticle
(b) Internal leaf structure
upperepidermis
mesophyllcells
lowerepidermis
outer membrane
inner membrane
thylakoid
stroma
(d) Chloroplast
(a) Leaves
(c) Mesophyll cell containing chloroplasts
Light
• Composed of tiny packets of energy called photons
• Energy of photons correspond to wavelength
– Long wavelength = low energy
– Short wavelength = high energy
Visible light
• Infinite number of wavelengths contained in sunlight
– Correspond to different colors
Light
• Three possible outcomes when photons strike an object
– Absorbed
– Reflected
– Transmitted
Reflected Absorbed Transmitted
Absorbed light
• Absorbed wavelengths generate heat, drive biological processes
Reflected light
• Reflected wavelengths reach the eye of observers
• Perceived as color
Thought question
• Why is white so bright?
Thought question
• Why are our pupils black?
Photosynthesis
• Sunlight is captured by pigments in chloroplasts
• Primarily chlorophyll
– Others (example: carotenoids)
• What colors does chlorophyll absorb? Reflect?
Chlorophylabsorbs
mainly blue and red light
Vitamin A
• Beta-carotene
– Plant pigment that gives orange vegetables their color
• Converted to vitamin A in animals
• Forms light-absorbing pigments in eye
– Blue and near-ultraviolet light
Photosynthesis
• Overall chemical reaction:
6 CO2 + 6 H2O + light energy C6H12O6 + 6 O2
Photosynthesis - VIPs
• Chloroplast
– Thylakoid
• Granum
• Lumen
– Stroma
Light reactions
• Light strikes chlorophyll and electrons are moved from PSII to ETC to PSI
• High energy electrons release energy to make
– ATP
– NADPH
• Low pH in thylakoid
lumen
• Leads to
photophosphorylation –
Generating ATP using
chemiosmosis in
chloroplast
Calvin cycle
• ATP and NADPH go on to fuel the Calvin cycle
• Light-independent reactions of photosynthesis
• Still in the chloroplast, just a different part(Light reactions) (Calvin cycle)
Where does carbon come from?
• Carbon in biomolecules of plants comes from CO2 in the air
• Carbon is “fixed” into larger organic molecules through the Calvin cycle
Energy
CO2
Calvin cycle -VIPs
• Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), ribulose bisphosphate (RuBP), CO2, glycerate 3-phosphate (3-PGA), glyceraldehyde 3-phosphate (G3P)
Products
• Products of photosynthesis: sugars, oxygen
• What happens to these products?
– Some sugar turned into tissues, stored for later use
– Oxygen and most sugars used to fuel cellular respiration in mitochondria
Reactants and products
• Light reactions– Reactants: Light energy, water
– Products: oxygen, ATP, NADPH
• Calvin cycle– Reactants: CO2, ATP, NADPH
– Products: Glucose
• Overall chemical reaction:
6 CO2 + 6 H2O + light energy C6H12O6 + 6 O2
Summary
• Photosynthesis
– Where: in chloroplast
– Uses: light, water, CO2
– Produces: sugar, O2, ATP, NADPH
LAB 4 – MITOSIS AND MEIOSIS
3 Parts to Lab 3
• Part 1: modeling mitosis– show:
• Starting chromosomes• Alignment of chromosomes in metaphase• Ending chromosomes
• Part 2: modeling meiosis– show:
• Starting chromosomes• Crossing over• Alignment of chromosomes in metaphase 1 • Alignment of chromosomes in metaphase 2• Ending chromosomes
• Part 3: observing mitosis onion root cells
• Extra: Prepare plates for next week’s lab
Learning Goals for Today:
• Describe the outcome of mitosis– Number of cells produced– Genetics of new cells compared to original
• Describe the outcome of meiosis– Number of cells produced– Genetics of new cells compared to original
• Observe and draw mitotic chromosomes from actual specimens (onion root tips)
Definitions
• Mitosis: cell division of a mother cell into two daughter cells, genetically identical to each other and to their parent cell
• Meiosis: a specialized type of cell division that reduces the chromosome number by half– DNA replication two rounds of cell division
– Mother cell 4 genetically distinct daughter cells
Cell Division is Only Part of the Cell Cycle
Fig. 9-7
G2: cellgrowthand preparationfor celldivision; organellesare duplicated
S: synthesisof DNA;chromosomesare duplicated
G1: cell growth andpreparation for synthesis
replication
mitosis
centromere
2 daughter cells
1 chromosome
1 duplicated chromosome
Chromosomes Are Copied Before Cell Division
Original cell
Each has 1 chromosome
Why do Cells Need to Divide?
• Make more cells
• Grow a larger organism
• Repair damage to organism
• Reproduction of the organism
Definitions
• Genome: A cell’s entire DNA, packaged as a double-stranded DNA molecule
• Chromosome: a double-stranded linear DNA molecule
– Human body (somatic) cells have 46 chromosomes (23 pairs)
– Human gametal cells have 23 chromosomes
Definitions
• Ploidy: number of sets of chromosomes in a cell
– Human somatic cells are diploid
– Human gametal cells are haploid
Definitions
Singlechromosome
DuplicatedChromosome,
“sister chromatids”
Homologous pair ofChromosomes
1A1B
1A 1A1A
1A 1B
2B2A
Homologous
Non homologous
Homologous
Sister chromatids
centromere
1A 1B
2B2A
sexchromosomes
Humans Have 23 Pairs of Chromosomes
1 set came from female parent1 set came from male parent
We are diploids (2 copies of each chromosome)
Often given number/letter names
chromosome 1Achromosome 1B
Chromosomes 1A and 1B are homologous chromosomes
Chromosomes with different numbers (like 1A and 4A) are non-homologous chromosomes
A
Copyright © 2011 Pearson Education, Inc.
The human life cycle
meiotic cell
division in
testes
meiotic cell
division in
ovaries
adults (2n)
egg (n)zygote (2n)
haploid (n)
diploid (2n)fusion of gametes
sperm (n)
embryo (2n)
baby (2n)
mitotic cell division,
differentiation, and growth
mitotic
cell division,
differentiation,
and growth
mitotic cell division,
differentiation,
and growth
Summary of Mitosis
• Prophase: chromosomes become visible
• Metaphase: chromosomes line up
• Anaphase: chromosomes move apart
• Telophase: two distinct cells form
Number of cells formed?
Cells same as original cell?
Prophase
Duplicatedchromosome
MITOSIS
Chromosomeduplication
Parent cell
2n 6
Metaphase
AnaphaseTelophase
2n 2n
Daughter cellsof mitosis
Introduction to Meiosis: the Big Picture
Starts with 1 original cell
Homologous chromosomes cross over
Ends with 4 non-identical cellsEach has half the DNA of the original cell
Meiosis is Essential for Sexual Reproduction
meioticcell division
fertilization
diploidparentalcells
diploidfertilizedegg
haploidgametes
2n
2n
2n n
n
Meiosis Allow For Genetic Recombination
• Genetic recombination is why most siblings are not identical
– Exception: identical twins
Genetic Recombination by Crossing Over of Homologous Chromosomes
Figure 13.8a
Prophase I Metaphase I Anaphase I Telophase I andCytokinesis
Centrosome(with centriole pair)
Sisterchromatids
Chiasmata
Spindle
Homologouschromosomes
Fragmentsof nuclearenvelope
Duplicated homologouschromosomes (red and blue)pair and exchange segments;2n 6 in this example.
Centromere(with kinetochore)
Metaphaseplate
Microtubuleattached tokinetochore
Chromosomes line upby homologous pairs.
Sister chromatidsremain attached
Homologouschromosomesseparate
Each pair of homologous chromosomes separates.
Cleavagefurrow
Two haploid cells form; each chromosomestill consists of two sister chromatids.
Figure 13.8b
Prophase II Metaphase II Anaphase IITelophase II and
Cytokinesis
Sister chromatidsseparate
Haploid daughtercells forming
During another round of cell division, the sister chromatids finally separate;four haploid daughter cells result, containing unduplicated chromosomes.
Figure 13.9a
Prophase
Duplicatedchromosome
MITOSIS
Chromosomeduplication
Parent cell
2n 6
Metaphase
AnaphaseTelophase
2n 2n
Daughter cellsof mitosis
MEIOSIS
MEIOSIS I
MEIOSIS II
Prophase I
Metaphase I
Anaphase ITelophase I
Haploidn 3
Chiasma
Chromosomeduplication Homologous
chromosome pair
Daughter cells of
meiosis I
Daughter cells of meiosis II
n n n n