Biochemistry Lecture - First Semester Final Exam - PDF

BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) PHOTOSYNTHESIS - Photosynthesis is the process used by autorrops to convert light energy into chemical energy in the form of glucose sugars....

BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) PHOTOSYNTHESIS - Photosynthesis is the process used by autorrops to convert light energy into chemical energy in the form of glucose sugars. - Photosynthesis occurs in two primary steps referred to as the light-dependent & light-independent - In plants, chlorophyll pigments in the chloroplast reactions. absorb energy from light and use it to catalyze a - The light-dependent stage takes place in the series of reactions. granum of the chloroplast, where light energy is used to split water (photolysis) into H+ ions, O2, and CHLOROPLAST e -. The H+ ions are then used to synthesis ATP via a chemical gradient. - The O2 is released as a byproduct. - H+ ions and ATP are used in the 'dark' reaction. - The ATP and H+ ions used to fix* CO2 molecules to sugar molecules in the light-independent reaction. - In total, 6 CO2 are needed in order to create one glucose. - *Fix = taken from the air and used to make organic 1. The Chloroplast is the organelle that carrie out photosynthesis. 2. The Organelle that is responsible for cellular respiration is the mitochondria. 3. The light absorbing pigment Chlorophyll is found in the thylakoid. 4. Chlorophyll absorbs red and blue light but reflects green light. - Sunlight consists of many wavelengths of light, but chlorophyll pigments power photosynthesis by absorbing the red and blue portions of the visible light spectrum. 1 BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) - Recall that we are only able to see light that is The biomass weight can be determined by dehydrating the reflected (not absorbed) by an object. Therefore plant and measuring the dry mass. green plants do not absorb green light. The following are needed for photosynthesis to occur, so altering them will change the photosynthetic rate. · Chlorophyll · Light · Carbon Dioxide · Water · Suitable temperature - Within the chloroplast, chlorophyll a absorbs the blue and red portions of the spectrum while ****These are limiting chlorophyll b absorbs higher wavelength blues. LIGHT INTENSITY Once the chlorophyll pigments are saturated with light, the photosynthetic rate can no longer increase. TEMPERATURE Low temperatures will prevent the photosynthesis from occurring. Too high will denature the proteins involved. CO2 CONCENTRATION When the reaction has been saturated with chlorophyll, the rate can not increase. However, it increases up to that point. 1. State that photosynthesis involves the conversion of light energy into chemical energy 2. State that light from the sun is composed of a range DIRECT MEASUREMENT of wavelengths (colors). 3. State that chlorophyll is the main photosynthetic Since it produces oxygen, the rate of pigment. photosynthesis can be determined by 4. Outline the difference in absorption of red, blue and observing the amount of bubbles that green light by chlorophyll. plants produce over time. 5. State that light energy is used to produce ATP, and to split water molecules (photolysis) to form oxygen You can also measure the amount of and hydrogen. available CO2 in an enclosed space 6. State that ATP and hydrogen (derived from the since it is consumed as photolysis of water) are used to fix carbon dioxide photosynthesis occurs. to make organic molecules. 7. Explain that the rate of photosynthesis can be measured directly by the production of oxygen or the uptake of carbon dioxide, or indirectly by an INDIRECT MEASUREMENT increase in biomass. 8. Outline the effects of temperature, light intensity and Photosynthetic rate can also be measured by measuring the carbon dioxide concentration on the rate of biomass of the plant over time a well as any changes in the photosynthesis. inorganic matter that the plant uses to grow. 2 BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) DNA AND RNA CENTRAL DOGMA OF MOLECULAR BIOLOGY DIFFERENCE BETWEEN DNA AND RNA 3 BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) NUCLEIC ACIDS - are nuclear biopolymers made up of monomers called nucleotides. They have two important functions: Hold the genetic information Variety of other functions Nucleic acids are biopolymers. "Bio" means they are found within biological systems and are not synthetically synthesized. These polymers are NITROGENOUS BASES made of repeated structural units, called as monomers (nucleotides). For example, proteins (one f the biopolymers in the body) – it’s repeated units are called amino acids Structure of nucleotides A single nucleotide consists of three important components: nitrogenous base sugar phosphate group. SUGAR - 5 carbon sugars are present in nucleic acids Nucleotides are present inside nucleic acids and are formed by combining a sugar molecule, a nitrogenous base, and phosphate groups. Sugars can be ribose or deoxyribose, which differ by one oxygen atom. Ribose is found in RNA, while deoxyribose is found in DNA. PHOSPHATE 4 BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) Example of Polymer: Starch o Monomers: Glucose molecules o Bond: Glycosidic bonds DNA as a Polymer: o Monomer: Nucleotides Nucleotide Structure 1. Phosphate Group: o Contains one phosphorus ion and four oxygen atoms. 2. Sugar: o Deoxyribose: A five-carbon sugar. 3. Nitrogenous Base: o Essential for genetic coding. DNA - Deoxyribonucleic Acid Location: Inside the nucleus of the cell. DNA REPLICATION Function: Stores and codes the genetic information of the body. DNA replication is the process by which DNA makes an Form: identical copy of itself during cell division. o Most of the time: Coiled, noodle-like structure in the nucleus. o During cell replication: Arranged into chromosomes to ensure DNA stability. Double Helix Model of DNA o Demonstrates DNA as a polymer (a molecule with repeating units which are called the monomers). 5 BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) DNA Polymerase: Adds nucleotides (energy from nucleotide triphosphates). Lagging Strand Short fragments joined by DNA ligase after primer removal. Proofreading DNA polymerase corrects errors in the newly synthesized DNA. Outcome: Two identical DNA helices are formed, ready for cell division. TRANSCRIPTION PROCESS OF DNA REPLICATION Unzipping DNA Helicase: Unzips DNA by breaking hydrogen bonds between base pairs, forming the replication fork. Single-Strand Binding Proteins: Prevent strands from rejoining. Directionality DNA Polymerase: Extends the 3' end of the strand using nucleotides, synthesizing from 5' to 3'. Leading Strand: Continuous synthesis. Lagging Strand: Discontinuous synthesis via Okazaki fragments., requiring repeated priming. Primer Formation Primase: Synthesizes RNA primer for DNA polymerase to start. Elongation 6 BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) Elongation: RNA polymerase adds complementary bases (e.g., uracil for adenine). Termination: RNA polymerase stops at terminators, releasing pre-mRNA. Pre-mRNA Processing Capping and Tailing: Protect RNA ends. Splicing: Removes introns to form mature RNA. Genetic Material DNA stores genetic information in the nucleus. Genes code for proteins; introns (non-coding regions) regulate or serve unknown purposes. TRANSLATION Gene Expression Transcription: Converts DNA to pre-messenger Gene Expression Overview: RNA (pre-mRNA). Gene expression involves two steps: transcription (copying DNA into mRNA) and translation (decoding Translation: Converts RNA to functional proteins. mRNA into proteins). Formation of PRE-MRNA Translation Process: Initiation: RNA polymerase binds to the promoter, separates DNA strands, and identifies the template strand (3' to 5'). 7 BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) 1. Initiation: Ribosome assembles around mRNA; Key Components: tRNA binds with methionine (start codon AUG). 2. Elongation: tRNA matches mRNA codons, transferring amino acids to form a polypeptide chain. mRNA carries genetic information. tRNA transfers amino acids. Ribosomes read mRNA and synthesize proteins. Complex structures composed of a small subunit (40S) and a large subunit (60S) in eukaryotes. These subunits join during translation to synthesize proteins. Location: In prokaryotes, translation happens in the cytoplasm. 3. Termination: Ribosome reads stop codon (UAG, In eukaryotes, it occurs in the cytoplasm or on the UAA, UGA), releasing the polypeptide. rough endoplasmic reticulum. Codons: A sequence of three mRNA bases (e.g., AUG for methionine, UUU codes for phenylalanine) corresponds to specific amino acids. 8 BIOCHEMISTRY LECTURE FIRST SEMESTER: FINAL EXAMINATION │LOPEZ, S.R. (BSN 1B) Post-Translation: Proteins may undergo modifications like folding or amino acid removal to become functional. 9 1