PHOTOSYNTHESIS.

Presentasi berjudul: "PHOTOSYNTHESIS."— Transcript presentasi:

1 PHOTOSYNTHESIS

2 Photosynthesis 6CO2 + 6H2O  C6H12O6 + 6O2
anabolisme, endergonik, carbon dioxida (CO2) proses yang menggunakan energi cahaya (photon) dan air (H2O) untuk menghasilkan molekul organik (glucose). 6CO H2O  C6H12O O2 glucose SUN photon klorofil Enzym

3 Struktur Daun Umumnya FS terjadi pada lapisan palisade.
Pertukaran gas antara CO2 dan O2 terjadi melalui stomata

4 Stomata (stoma) Pori-pori pada permukaan daun, tempat terjadinya pertukaran air dan gas antara tumbuhan dan atm. Oxygen (O2) Guard Cell Carbon Dioxide (CO2)

5 Struktur Kloroplas Membran bagian dalam thylakoid.
Bagian yang menebal disebut thylakoids. Satu grup thylakoid disebut granum. (jamak – grana) Stroma cairan disekitar (yang meyelimuti) thylakoids.

6 Chloroplast Organel dimana photosynthesis berlangsung Stroma
Membran luar Thylakoid Granum Membran dalam

7 Thylakoid Thylakoid Membrane Granum Thylakoid Space

8 Molekul Klorofil Terdapat pada membran thylakoid.
Terdapat Mg++ pada pusat. Pigmen klorofil menangkap energi cahaya (photon) dengan menyerap panjang gelombang tertentu (biru-420 nm dan merah -660 nm yang paling penting). Tumbuhan tampak hijau ?

9 Pigmen Klorofil A merupakan pigmen FS yang paling penting.
Pigmen lain disebut antena atau pigmen tambahan juga terdapat di dalam daun. Klorofil B Carotenoids (oranye/ merah) Xanthophylls (kuning / coklat) Pigmen ini terbenam di dalam membran kloroplas yang disebut photosystems.

10 Panjang gelombang Cahaya (nm)
400 500 600 700 Short wave Long wave (more energy) (less energy)

11 Absorpsi Cahaya oleh Klorofil
violet blue green yellow orange red Absorpsi Panjang gelombang

12 Reaksi Redox Transfer satu atau lebih elektron dari satu reaktan ke yang lain Dua jenis: 1. Oxidasi 2. Reduksi

13 Reaksi Oksidasi 6CO2 + 6H2O  C6H12O6 + 6O2
Hilangnya elektron dari satu senyawa Atau bertambahnya oksigen pada suatu senyawa. Oxidation glucose 6CO H2O  C6H12O O2

14 Reaksi Reduksi 6CO2 + 6H2O  C6H12O6 + 6O2
Bertambahnya elektron pada suatu senyawa Atau hilangnya Oxygen dari suatu senyawa. Reduction glucose 6CO H2O  C6H12O O2

15 Tahapan Photosynthesis
Dua tahapan utama (reaksi). 1. Reaksi Cahaya atau Reaksi yang tergantung cahaya Menghasilkan energi dari energi cahaya (photon) dalam bentuk ATP dan NADPH. Siklus Calvin atau Fikasasi Carbon atau Fixation C3 :Tidak tergantung cahaya Menggunakan energy (ATP and NADPH) dari reaksi cahaya untuk membuat gula (glucose).

16 1. Reaksi Cahaya (Aliran Elektron)
Berlangsung di membran Thyllakoid Selama Reaksi Cahaya, ada dua jalur aliran elektron. A. Aliran elektron siklik B. Aliran elektron nonsiklik

17 A. Aliran Elektron Siklik
Terjadi di membran thylakoid. Menggunakan hanya Photosystem I P700 - klorofil a Menggunakan Rantai Transport Elektron (RTE). Hanya menghasilkan ATP ADP ATP P

18 A. Aliran Elektron Siklik
P700 Primary Electron Acceptor e- ATP Dihasilkan RTE Photosystem I Accessory Pigments SUN Photons

19 B. Aliran Elektron Nonsiklik
Berlangsung di Thyllakoid membran Menggunakan PS II dan PS I P680 pusat reaksi (PSII) – klorofil a P700 pusat reaksi (PS I) – klorofil a Menggunakan rantai Transport Elektron Menghasilkan O2, ATP dan NADPH

20 B. Aliran Elektron Nonsiklik
P700 Photosystem I P680 Photosystem II Elektron Acceptor primer ETC Reaksi Enzym H2O 1/2O2 + 2H+ ATP NADPH Photon 2e- SUN

21 B. Aliran Elektron Nonsiklik
ADP +  ATP NADP+ + H  NADPH Oxygen berasal dari peruraian H2O, bukan CO2 H2O  /2 O2 + 2H+ P (Reduced) (Reduced) (Oxidized)

22 Chemiosmosis Mendorong synthesis ATP Berlangsung di membran thylakoid.
Menggunakan RTE dan ATP synthase (enzyme) untuk membuat ATP. Photophosphorylasi: Penambahan phosphate ke ADP untuk membuat ATP.

23 Chemiosmosis ADP + P ATP PS II PS I E T C (Pompa Proton )
H+ H+ ATP Synthase Konsentrasi H+ Tinggi H+ ADP + P ATP PS II PS I E T C rendah Rongga Thylakoid SUN (Pompa Proton )

24 Siklus Calvin Fikasai Carbon (tidak tergantung cahaya ).
Tumbuhan C3 (80% tumbuhan di bumi). Berlangsung di stroma. Menggunakan ATP dan NADPH dari reaksi cahaya. Menggunakan CO2. Untuk menghasilkan glukosa: Perlu 6 putaran dan menggunakan 18 ATP dan 12 NADPH.

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27 Siklus Calvin ( Fiksasi C3)
6CO2 6C-C-C-C-C-C 6C-C-C 6C-C-C-C-C 12PGA RuBP 12G3P (unstable) 6NADPH 6ATP C-C-C-C-C-C Glucose (6C) (36C) (30C) C3 glucose

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30 Photorespirasi Terjadi pada saat panas, kering, dan hari cerah
Stomata tertutup. Fixasi O2 bukan CO2 (instead of CO2) Menghasilkan Molekul 2-C bukan (instead gula berkarbon 3-C ). Tidak menghasilkan gula dan ATP.

31 Photorespirasi Tanaman beradaptasi untuk mengurangi dampak fotorespirasi . 1. Tumbuhan C4 2. Tumbuhan CAM

32 Tumbuhan C4 Panas dan lingkungan lembab (kelembaban tinggi).
15% tumbuhan (rumput-rumputan, jagung, tebu). Fotosintesis berlangsung di dua tempat. Reaksi terang – pada sel-sel mesofil Siklus Calvin - pada sel-sel selubung (bundle sheath cells).

33 ANATOMI DAUN JAGUNG (Zea mays sp.)

34 Tumbuhan C4 Sel Mesofil Sel Bundle (Selubung) C3 CO2 C-C-C PEP C-C-C-C
Malat ATP Sel Bundle (Selubung) C-C-C Asam piruvat C-C-C-C CO2 C3 Malat Di transport glukosa Vascular Tissue

35 Tumbuhan CAM Panas, lingkungan kering . 5% dari tumbuhan (cactus)
Stomata menutup pada siang hari . Stomata membuka pada malam hari. Reaksi terang - berlangsung pada siang hari Siklus Calvin – berlangsung bila CO2 tersedia .

36 Tumbuhan CAM Malam hari (Stomata terbuka Siang hari (Stomata menutup)
Vacuole C-C-C-C Malate CO2 C3 C-C-C Pyruvic acid ATP PEP glucose

37 Diskusi Mengapa tumbuhan CAM menutup stomatanya pada siang hari ?

38 Faktor –Faktor yang Mempengaruhi Laju Fotosintesis & Jalur alternatif

39 Tujuan: - Membahas faktor-faktor yang mempengaruhi laju fotosintesis. - Membahas jalur alternatif yang digunakan tumbuhan untuk membuat glukosa

40 Faktor yang mempengaruhi fotosintesis
Tiga faktor lingkungan penting yang dapat mempengaruhi laju fotosintesis: Intensitas cahaya Kadar CO2 Temperatur

41 Intensitas Cahaya Semakin tinggi intensitas cahaya laju FS meningkat kemudian konstan. Laju FS yang konstan menunjukkan laju FS maximum

42 Kadar CO2 The Effect of the Level of Carbon Dioxide on the Rate of Photosynthesis Semakin tinggi kadar CO2 , laju FS meningkat, kemudian konstan . Laju FS yang konstan menunjukkan laju FS maximum

43 The Effect Temperature on the Rate of Photosynthesis
Temperatur/Suhu Awalnya, semakin meningkat temperatur laju FS meningkat. Laju FS maximum kemudian menurun sebab: Enzym yg mengkatalisa reaksi menjadi tidak aktif. Stomata mulai menutup, CO2 yang masuk melalui stomata terhambat. The Effect Temperature on the Rate of Photosynthesis

44 Tumbuhan C3 REVIEW: Siklus Calvin, CO2 digunakan untuk mensintesis gula Tumbuhan C3 (kedelai, wheat, padi) hanya menggunakan Siklus Calvin un tuk memfixaxi CO2 Disebut Tumbuhan C3, karena CO2 pertama-tama berikatan dengan senywa berkarbon 3. Tumbuhan ini beroperasi pada siang hari

45 Jalur Alternatif Beberapa tumbuhan di daerah panas, kering beradaptasi untuk meminimalkan kehilangan air sementara FS tetap berlangsung. Tumbuhan C4 Tumbuhan CAM CO2 tidak segera/langsung masuk Siklus Calvin seperti halnya tumbuhan C3

46 Tumbuhan C4 Stomata sebagian menutup (celah lebih kecil) pada siang hari Memiliki jalur khusus untuk memfixaxi kadar CO2 yang rendah dan terbentuk senyawa berkarbon 4 yang masuk Siklus Calvin. Contoh: Tebu, jagung These 4 carbon compounds are then transported to other cells and then enter the Calvin Cycle.

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48 Tumbuhan CAM Tumbuhan CAM membuka stomata pada malam hari dan menutup pada siang hari Memiliki jalur khusus untuk menyerap CO2 pada malam hari untuk mensintesis berbagai senyawa asam organik Kemudian pada siang hari, enzym-enzym menguraikan asam organik tersebut, dengan melepas CO2 yang kemudian masuk ke siklus Calvin. Examples: cacti and pineapples Jade and snake plants crassulacean acid metabolism

49 Online Simulation Examined the effect of varying colors of light, light intensity, and amount of carbon dioxide on the rate of photosynthesis Measured the number of bubbles (oxygen) after 30 seconds

50 Translokasi Fotosintat:Sources and sinks
Any exporting region that produces photosynthate above and beyond that of its own needs Sink: any non-photosynthetic organ or an organ that does not produce enough photosynthate to meets its own needs

51 Bagaimana fotosintat di translokasikan keseluruh bagian tumbuhan
Photosynthesis New growth Translocation A system of vascular tissue runs through all higher plants. It evolved as a response to the increase in the size of plants, which caused an progressing separation of roots and leaves in space. The phloem is the tissue that translocates assimilates from mature leaves to growing or storage organs and roots.

52 Photosynthesis provides a
sugar source New growth is a sugar sink Translocation Sources and sinks Direction of transport through phloem is determined by relative locations of areas of supply, sources and areas where utilization of photosynthate takes place, sinks. Source: any transporting organ capable of mobilizing organic compounds or producing photosynthate in excess of its own needs, e.g., mature leaf, storage organ during exporting phase of development. Sink: non photosynthetic organs and organs that do not produce enough photoassimilate to meet their own requiements, e.g., roots, tubers, develpoping fruits, immature leaves.

53 Multiple sources and sinks
The flow of water in plants is almost always from roots to leaves. Translocation of sucrose can be in any direction – depending on source and sink location and strength. Multiple sources and sinks Source Developing apex Sink Source Translocation Examples: Beta maritima (wild beet) root is a sink during the first growing season. In the second season the root becomes a source, sugars are mobilized and used to produce a new shoot. In contrast, in cultivated sugar beets roots are sinks during all phases of development. Source Sink Sink Sink Sink Sink

54 Translokasi Fotosintat
Penyaluran fotosintat/gula terjadi dari sugar source (sel penghasil) ke sugar sink (sel gudang). Teori : aliran tekanan/massa gula dialirkan dari lokasi dengan konsentrasi gula tinggi ke rendah. Mekanisme : o Gula dimuat ke dalam floem secara transpor aktif. o Air masuk ke dalam floem secara osmosis. o Gula dialirkan dari sugar source ke sugar sink. Air melalui proses osmosis kembali ke xilem. BIO100/101 Tumbuhan 2 2 24

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56 The mechanism of phloem transport The Pressure-Flow Model

57 The Pressure-Flow Model
Translocation is thought to move at 1 meter per hour Diffusion too slow for this speed The flow is driven by an osmotically generated pressure gradient between the source and the sink. Source Sugars (red dots) is actively loaded into the sieve element-companion cell complex Called phloem loading Sink Sugars are unloaded Called phloem unloading

58 The Pressure -Flow Model
yw = ys + yp + yg In source tissue, energy driven phloem loading leads to a buildup of sugars Makes low (-ve) solute potential Causes a steep drop in water potential In response to this new water potential gradient, water enters sieve elements from xylem Thus phlem turgor pressure increases In sink tissue, phloem unloading leads to lower sugar conc. Makes a higher (+ve) solute potential Water potential increases Water leaves phloem and enters sink sieve elements and xylem Thus phloem turgor pressure decreases

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60 The Pressure -Flow Model
yw = ys + yp + yg In source tissue, energy driven phloem loading leads to a buildup of sugars Makes low (-ve) solute potential Causes a steep drop in water potential In response to this new water potential gradient, water enters sieve elements from xylem Thus phlem turgor pressure increases In sink tissue, phloem unloading leads to lower sugar conc. Makes a higher (+ve) solute potential Water potential increases Water leaves phloem and enters sink sieve elements and xylem Thus phloem turgor pressure decreases

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62 The Pressure-Flow Model
So, the translocation pathway has cross walls Allow water to move from xylem to phloem and back again If absent- pressure difference from source to sink would quickly equilibrate Water is moving in the phloem by Bulk Flow No membranes are crossed from one sieve tube to another Solutes are moving at the same rate as the water Water movement is driven by pressure gradient and NOT water potential gradient

63 Phloem Loading: Where do the solutes come from?
Triose phosphate – formed from photosynthesis during the day is moved from chloroplast to cytosol At night, this compound, together with glucose from stored starch, is converted to sucrose Both these steps occur in a mesophyll cell Sucrose then moves from the mesophyll cell via the smallest veins in the leaf to near the sieve elements Known as short distance pathway – only moves two or three cells

64 What is transported in phloem?

65 Phloem Loading: Where do the solutes come from?
Triose phosphate – formed from photosynthesis during the day is moved from chloroplast to cytosol At night, this compound, together with glucose from stored starch, is converted to sucrose Both these steps occur in a mesophyll cell Sucrose then moves from the mesophyll cell via the smallest veins in the leaf to near the sieve elements Known as short distance pathway – only moves two or three cells

66 Summary Pathway of translocation: Patterns of translocation:
Sugars and other organic materials are conducted throughout the plant in the phloem by means of sieve elements Sieve elements display a variety of structural adaptations that make the well suited for transport Patterns of translocation: Materials are translocated in the phloem from sources (usually mature leaves) to sinks (roots, immature leaves)

67 Summary Materials translocated in phloem: Rate of translocation:
Translocated solutes are mainly carbohydrates Sucrose is the most common translocated sugar Phloem also contains: Amino acids, proteins, inorganic ions, and plant hormones Rate of translocation: Movement in the phloem is rapid, well in excess of rates of diffusion Average velocity is 1 meter per hour

68 General diagram of translocation
Physiological process of loading sucrose into the phloem Pressure-flow Phloem and xylem are coupled in an osmotic system that transports sucrose and circulates water. Physiological process of unloading sucrose from the phloem into the sink

69 Pressure flow schematic
The pressure-flow process Build-up of pressure at the source and release of pressure at the sink causes source-to-sink flow. At the source phloem loading causes high solute concentrations. y decreases, so water flows into the cells increasing hydrostatic pressure. At the sink y is lower outside the cell due to unloading of sucrose. Osmotic loss of water releases hydrostatic pressure. Xylem vessels recycle water from the sink to the source. Pressure flow schematic