exam 3 cell func + struct

Kinetic energy

Energy that an object has when it is moving, such as a moving car

Potential energy

Energy stored in an object because of its position, like a book on a shelf

Thermal energy

Energy caused by the movement of particles in a substance. Faster-moving particles

produce higher temperatures

Chemical energy

Energy stored in chemical bonds that can be released or absorbed during a chemical

reaction, such as burning fuel

Define metabolism.

Metabolism is the total set of life-sustaining chemical reactions that happen within the cells of living organisms to convert food into energy and building blocks

Define the 1st law of thermodynamics

The first law of thermodynamics states that energy cannot be created or destroyed, but can only be transformed from one form to another or transferred between a system and its surroundings

Define the 2nd law of thermodynamics

the total entropy (disorder) of an isolated system must always increase or remain constant over time

Write the equation for free energy and define all the components (variables)

DeltaG=DeltaH-TDeltaS

ΔG (Change in Gibbs free energy): The energy available to do useful work and indicates whether a

reaction is spontaneous.

ΔH (Change in enthalpy): The heat absorbed or released during a reaction at constant pressure.

T (Temperature): The temperature in Kelvin (K).

ΔS (Change in entropy): The change in disorder or randomness of a system.

Define (write the equation) for DeltaG. What does a negative DeltaG mean? What does a

positive DeltaG mean?

DeltaG=DeltaH-TDeltaS

Negative ΔG (ΔG < 0): The reaction is spontaneous and can occur without an additional energy input.

Positive ΔG (ΔG > 0): The reaction is nonspontaneous and requires an energy input to proceed.

ΔG = 0: The reaction is at equilibrium.

What is activation energy?

Activation energy (Ea) is the energy needed to start a chemical reaction by allowing the reactants to reach the transition state

Name two ways enzymes can be denatured.

extreme temperature and extreme pH levels

Name two ways that enzyme activity is controlled

Temperature and pH: Changes in temperature or pH can affect an enzyme's shape and activity. Inhibitors: Molecules that bind to enzymes and decrease or stop their activity

Compare and contrast endergonic and exergonic

Exergonic reactions release free energy and occur spontaneously, while endergonic reactions absorb free energy and are non-spontaneous

Compare and contrast competitive and noncompetitive inhibition of enzymes

Competitive inhibition: The inhibitor competes with the substrate for the enzyme's active site, preventing the substrate from binding.

Noncompetitive inhibition: The inhibitor binds to a different site on the enzyme, changing its activity and reducing the reaction rate.

Both types of inhibition decrease enzyme activity, but competitive inhibition can be overcome by adding more substrate, while noncompetitive inhibition cannot.

Define allosteric regulation

process where a molecule binds to a site other than a protein's active site, changing its shape and altering its activity

What are the three stages of aerobic respiration?

glycolysis, the Krebs cycle (or citric acid cycle), and the electron transport chain (with oxidative phosphorylation)

What is the overall purpose of aerobic respiration? What process begins respiration (in general) and where does this process take place?

The primary purpose of aerobic respiration is to convert nutrients like glucose and oxygen into usable cellular energy in the form of ATP. Cellular respiration begins with a process called glycolysis, which takes place in the cytoplasm (or cytosol) of the cell.

What are the two pathways a cell can take from glycolysis? What determines which of these pathways is utilized?

The two main pathways that can follow glycolysis are cellular respiration (specifically the Krebs cycle, or citric acid cycle) and fermentation. After glycolysis, a cell directs pyruvate into either aerobic cellular respiration or anaerobic fermentation.

How many ATP molecules are produced from 1 complete cycle of aerobic respiration?

A complete cycle of aerobic respiration from one glucose molecule produces a net total of 30 to 32 ATP molecules in modern scientific calculations, though older textbooks traditionally cite 36 to 38 ATP.

How many ATP are needed to drive glycolysis?

Glycolysis requires an investment of 2 ATP molecules to start and drive the process per

molecule of glucose

What is the starting material for glycolysis? What are the end products and how

many molecules of each product are produced?

The starting material is 1 glucose molecule (6 carbons). Glycolysis produces 2 pyruvate, 2

NADH, and a net gain of 2 ATP

What is the second stage of the aerobic pathway and where does it take place?

The second stage is pyruvate oxidation. It takes place in the mitochondrial matrix in eukaryotic cells.

Describe the process of the pyruvate oxidation. What are the starting materials? What are the products?

Pyruvate is converted into acetyl-CoA. During this process, CO₂ is released and NADH is

produced. Starting material: 2 pyruvate Products: 2 acetyl-CoA, 2 CO₂, and 2 NADH

What are the starting materials for the Citric Acid/Kreb’s cycle? What are the end

products?

The main starting material is acetyl-CoA, which enters the cycle by combining with oxaloacetate.

For each glucose molecule, the cycle produces:

4 CO₂

6 NADH

2 FADH₂

2 ATP (or GTP)

What is the purpose of electron transfer phosphorylation? Where does it take

place?

Its purpose is to use the energy from electrons to produce ATP. It occurs along the electron transport chain and ATP synthase in the inner mitochondrial membrane.

What is the role of NADH and FADH2?

NADH and FADH₂ are electron carriers. They carry high-energy electrons to the electron

transport chain, where their electrons provide energy used to make ATP.

What is the final electron acceptor? What is produced by this joining?

The final electron acceptor is oxygen (O₂). Oxygen combines with electrons and hydrogen ions to produce water (H₂O).

What drives the production of ATP?

The proton (H⁺) gradient across the inner mitochondrial membrane drives ATP production. As H⁺ ions flow through ATP synthase, the energy is used to make ATP.

Describe two types of anaerobic respiration and explain how they are different?

Two types are lactic acid fermentation and alcoholic fermentation. Lactic acid fermentation: Pyruvate is converted into lactate. It occurs in some bacteria and in muscle cells when oxygen is limited. Alcoholic fermentation: Pyruvate is converted into ethanol and CO₂. It commonly occurs in yeast. The main difference is the final products: lactic acid fermentation produces lactate, while alcoholic fermentation produces ethanol and carbon dioxide

What is the general purpose of photosynthesis? Describe the energy conversion that takes place.

Photosynthesis converts light energy into chemical energy stored in glucose. Plants use CO₂ + H₂O + light energy to make glucose and O₂

What are pigments and absorption spectrums? Know how to read absorption spectrums

(what colors are absorbed and which are reflected).

Pigments are molecules that absorb certain wavelengths/colors of light.

An absorption spectrum shows which wavelengths a pigment absorbs.

How to read one:

High absorption = that color/wavelength is being absorbed.

Low absorption = that color is mostly reflected or transmitted.

What colors are absorbed by chlorophyll a and b?

blue/violet and red

Also a little bit of green

What is the summary equation for photosynthesis?

6CO2 + 6H2O + light energy -> C6H12O6 + 6O2

Carbon dioxide + water + light -> glucose + oxygen

Where does photosynthesis take place? Describe the structure of this organelle.

Photosynthesis occurs in the chloroplast.

A chloroplast contains:

Outer and inner membranes

Stroma → fluid-filled space

Thylakoids → flattened membrane sacs

Grana → stacks of thylakoids

Thylakoid space/lumen → inside of the thylakoids

What is produced in the thylakoids? What is used in the stroma?

Thylakoids produce:

● ATP

● NADPH

● O₂

Stroma uses:

● ATP

● NADPH

● CO₂

These are used to make G3P, which can ultimately be used to make glucose.

Where do light dependent reactions take place? Light independent reactions?

Light-dependent reactions: thylakoid membranes

Light-independent reactions: stroma

What 3 events occur during light dependent reactions?

Water is split, producing O₂, electrons, and H⁺.

ATP is produced using the H⁺ gradient.

NADPH is produced when electrons are transferred to NADP⁺.

Describe a photosystem

A photosystem is a group of pigments and proteins in the thylakoid membrane

What is a photosystem’s purpose?

Its purpose is to capture light energy and excite electrons.

There are two major photosystems:

Photosystem II (PSII)

Photosystem I (PSI)

How is the hydrogen ion gradient generated during light dependent reactions?

H⁺ becomes concentrated inside the thylakoid lumen through several processes: Water is split, adding H⁺ to the lumen. The electron transport chain uses energy from electrons to pump H⁺ into the lumen. This creates a high concentration of H⁺ inside the thylakoid.

What is an electron acceptor in light dependent reactions?

The final electron acceptor is:

NADP⁺

It accepts electrons and H⁺ to become:

NADPH

How is ATP generated in light dependent reactions?

The H⁺ gradient causes H⁺ to flow through ATP synthase.

This movement provides energy to convert:

ADP + Pi → ATP

This process is called chemiosmosis

What is the name of the cycle that makes up the light independent reactions? Where do these reactions take place?

The Calvin cycle.

What is produced in the calvin cycle ?

The Calvin cycle uses:

CO₂

ATP

NADPH

It produces G3P, a 3-carbon sugar.

Where do these reactions take place? calvin cycle

It occurs in the stroma of the chloroplast.

Where does the CO2 needed to drive this cycle come from? What is the purpose of CO2 in this context?

CO₂ comes from the atmosphere and enters the plant through openings called stomata.

Its purpose is to provide the carbon needed to build carbohydrates during the Calvin cycle.

What is the low-energy molecule produced in light-independent reactions? The high-energy molecule?

Low-energy molecule produced: G3P → a 3-carbon sugar

High-energy molecules used by the Calvin cycle: ATP, NADPH

How many molecules of glucose are produced by one round of the calvin cycle?

One round of the Calvin cycle produces 1/6th of a glucose molecule

Compare and contrast photoautotrophs, chemoautotrophs, and heterotrophs.

Photoautotrophs: Use light energy to make their own food from CO₂.

Chemoautotrophs: Use energy from chemicals to make their own food from CO₂.

Heterotrophs: Get their energy and carbon from consuming organic matter from other organisms.

Four reasons cells divide

Growth, Repair, Replace old or damaged cells, Reproduction

Chromosome

DNA containing genetic information.

Chromatid

one copy of a duplicated chromosome

centromere

region joining sister chromatids

duplicated chromosome

2 sister chromatids

unduplicated chromosome

1 chromatid

haploid (n)

one set; human sperm and eggs have 23

diploid (2n)

two sets of chromosomes; human body cells have 4

phases of the cell cycle

G1: Cell grows.

S: DNA replicates.

G2: Cell prepares for division.

M phase: Mitosis and cytokinesis.

Mitosis

the process where a single eukaryotic cell replicates its chromosomes and divides to form two genetically identical daughter cells

Meiosis

a specialized type of cell division in sexually reproducing organisms that reduces the chromosome number by half, turning one diploid cell into four haploid gametes

meiosis vs mitosis

Mitosis: growth, tissue repair, asexual reproduction

meiosis: Sexual reproduction

G1

growth and normal cell functions

s

dna is copied

g2

more growth and preparation

Stages of mitosis

Prophase: Chromosomes condense; spindle forms.

Metaphase: Chromosomes line up in the middle.

Anaphase: Sister chromatids separate.

Telophase: Two nuclei form

What separates during mitotic anaphase?

sister chromatids

Chromosome number in mitosis

Stays the same.

One cell divides into two genetically similar cells

cytokinesis

Division of the cytoplasm.

Animal cells: Membrane pinches inward.

Plant cells: Cell plate forms

Genes and gametes

Gene: DNA segment containing instructions for a functional product.

Gamete: Haploid reproductive cell (sperm or egg).

Meiosis I vs. meiosis II

Meiosis I: Homologous chromosomes separate.

Meiosis II: Sister chromatids separate.

Stages of meiosis I

Prophase I: Homologous chromosomes pair; crossing over occurs.

Metaphase I: Homologous pairs line up in the middle.

Anaphase I: Homologous chromosomes separate.

Telophase I: Two haploid cells form with duplicated chromosomes.

Crossing over

DNA exchange between non-sister chromatids of homologous chromosomes.

Occurs in prophase I.

Increases genetic diversity

Random arrangement

Homologous pairs line up randomly in metaphase I.

Creates different chromosome combinations in gametes.

Outcomes of meiosis

After meiosis I: 2 haploid cells with duplicated chromosomes.

After meiosis II: 4 haploid cells with unduplicated chromosomes.

Stages of meiosis II

Prophase II: Spindle forms.

Metaphase II: Chromosomes line up in the middle.

Anaphase II: Sister chromatids separate.

Telophase II: Four haploid cells form.

Male vs. female gamete formation

Spermatogenesis: Usually produces 4 sperm.

Oogenesis: Usually produces 1 egg and polar bodies.

Egg formation involves unequal cytoplasm division.

Haploid or diploid? spermatogonium

Diploid

Haploid or diploid? Primary spermatocyte

diploid

Haploid or diploid? Secondary spermatocyte

haploid

Haploid or diploid? Spermatids

haploid

Haploid or diploid? Oogonium

diploid

Haploid or diploid? Primary oocyte

diploid

Haploid or diploid? Secondary oocyte:

haploid

Haploid or diploid? ovum

haploid

Chromosome number in meiosis

Reduced by half.

Humans: 46 chromosomes → 23 per final haploid cell.

Meiosis produces four haploid cells.

helicase

separates dna

primase

adds rna primers

polymerase

builds new DNA

ligase

joins fragments

okazaki fragments

short pieces on lagging strand

5’ to 3’

direction of new dna synthesis

A - T

G - C

base excision repair

removes and replaces individual damaged or incorrect bases

nucleotide excision repair

Removes damaged sections of DNA, such as those caused by UV radiation, and replaces them.

mismatch repair

Fixes incorrectly paired bases that remain after DNA replication.

repair mechanism similarities (3)

correct dna damage or errors, maintain genetic stability, all involve removing or correcting incorrect dna and replacing it with correct sequence

Telomeres

repetitive DNA sequences found at the ends of linear chromosomes

Telomeres protect

chromosomes from losing important genetic information

Telomeres prevent

chromosome ends from being damaged or incorrectly joined

Telomeres become

shorter as cells divide