STUDY GUIDE – ENERGY IN CELLS
ATP - (Adenosine TriPhosphate): Energy storage molecule.
· Composed of Adenosine, 3 phosphaters
· Energy is released when bond between 2 phosphates is broken
· ATP turns into ADP when energy is used. ADP then changes back to ATP when energy is stored.
PHOTOSYNTHESIS
Plants use the sun’s energy to produce food (carbohydrates).
Chloroplasts: organelle that converts light energy into chemical energy. Chlorophyll is a green pigment in the chloroplast
Reactants Products
Chemical Formula: 6CO2 + 6H2O à C6H12O6 + 6O2
Carbon dioxide and water react to form glucose and oxygen gas
Stage 1: Light Dependent Reactions (requires light)
Chloroplasts absorb sunlight. The water molecule is split. A molecule of ATP and oxygen gas are produced.
Stage 2: Light Independent Reactions: “Calvin Cycle” (does not require light)
ATP from stage one used to turn carbon dioxide into glucose (sugar).
The glucose (carbs) produced are used as “food” for plants, or is eaten by animals for energy.
CELLULAR RESPIRATION
Animals and plants break down glucose to make energy (ATP)
Mitochondria: are organelles that convert chemical energy in glucose into ATP energy molecules.
Reactants Products
Chemical Formula: C6H12O6 + 6O2 à 6CO2 + 6H2O and ATP*
Glucose and oxygen react to form carbon dioxide, water, and ATP
The end products of photosynthesis are the starting reactants of respiration.
The end products of respiration are the starting reactants of photosynthesis.
Step 1: Glycolysis
Glucose is broken down into pyruvic acid. (2 ATP produced) Occurs in cytoplasm
Step 2: Kreb’s Cycle (If oxygen present = aerobic)
Pyruvic acid enters the mitochondria and is broken down. CO2 released (2 ATP produced)
Step 3: Electron Transport Chain ; ETC (aerobic)
Substance from the Kreb’s cycle is broken down. H20 released. (MOST ATP produced)
When NO oxygen present = Anaerobic respiration
Fermentation no O2
Temporary process that produces a small amount of ATP when oxygen is not available.
· Lactic Acid fermentation: glucose broken down into lactic acid and ATP (muscle cells)
· Alcoholic fermentation: glucose broken down into alcohol and ATP (yeast and bacteria)
CELLULAR REPRODUCTION
The Cell Cycle:
Interphase: G1 – growth and normal cell activities (Longest Phase)
S - DNA Replication (DNA doubles)
G2 – the cell prepares to divide
Mitosis – the nucleus of the cell divides
Cytokinesis – the cytoplasm divides (2 identical daughter cells formed)
Sister Chromatids – identical chromosomes held together by a centromere
ASEXUAL REPRODUCTION - MITOSIS (PMAT)
§ Occurs in somatic (body) cells
§ Produces 2 identical diploid daughter cells “clones” Diploid – 2n, 46 chromosomes
§ Sister chromatids separate
Prophase – nuclear membrane breaks down, spindle fibers form, sister chromatids form, centrioles move the poles
Metaphase – sister chromatids line up in the center of the cell attached to spindle fibers by the centromere
Anaphase – sister chromatids separate and move to opposite poles of the cell
Telophase – 2 new nuclei form
Cytokinesis: Animal cell – cleavage furrow forms and cytoplasm divides
Plant cell – cell plates form to create new cell wall between cells
Cancer: an abnormal cell that does not obey cell division checkpoints
Benign (does not spread) Malignant (spreads)
SEXUAL REPRODUCTION - MEIOSIS (2 divisions)
§ Creates gametes (sex cells) Male=sperm Female=egg
§ Produces 4 haploid daughter cells
§ Provides genetic diversity (variety of genetic traits)
Homologous Chromosome Pair: Pair of chromosomes (one maternal, one paternal)
Crossing Over: homologous chromosomes are lined up together during prophase I, overlapping allows an
exchange of DNA between the two. (genetic diversity)
Meosis I –
Prophase I: nuclear membrane breaks down
Homologous pairs form
Metaphase I: Homologous pairs line up in the center
Anaphase I: Homologous pairs separate
Telophase I: 2 new nuclei form
Cytokinesis: cytoplasm splits, 2 daughter cells formed
Meosis II –
Prophase II – nuclear membrane breaks down
Sister chromatids form
Metaphase II – sister chromatids line up in center
Anaphase II – sister chromatids separate
Telophase II – 2 new nuclei form in each cell
Cytokinesis: cytoplasm splits, 4 haploid gametes formed
Fertilization Sperm + Egg à Zygote
(23) (23) (46)
Non-disjunction: when the chromosomes do not separate properly during meiosis.
§ Can cause genetic defects. Ex. Down syndrome, Trisomy 18
Mutation: an error in a DNA code that is passed to offspring through the gametes.