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Which of the following best describes the number of cells in a human body?
What is the average size of a cell?
What is protoplasm responsible for in cells?
Which of the following elements are the primary elements in biomolecules?
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What are the essential major organic compounds in cells?
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True or false: Cells are the building blocks of all living things.
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True or false: There are about 200 different cell types in mammals.
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True or false: Protoplasm is responsible for the complex process of metabolism in cells.
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True or false: Water is an inorganic compound found in cells.
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True or false: Lipids are the most important elementary building block of a cell.
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True or false: Nucleic acids are organic compounds found in cells.
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True or false: The average size of a cell is about 0.002 cm.
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True or false: Proteins are made up of amino acids NH2 (amin) and COOH (carboxylic acid).
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True or false: Structural proteins provide the body with its shape and form, and are a source of heat and energy.
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True or false: Enzymatic proteins function as organic catalysts, affecting the rate of chemical reactions without being altered themselves.
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True or false: Repair enzymes help the cell recover from radiation-induced damage.
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True or false: Carbohydrates are chains of sugar molecules that primarily function as long-term energy storage.
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True or false: Lipids are also known as fatty acids.
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True or false: Nucleic acids are large complex macromolecules made from nucleotides.
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True or false: Mitosis is the division of somatic cells.
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True or false: Mitosis results in two identical daughter cells.
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True or false: Daughter cells produced in mitosis have the same number of chromosomes as the parent cell.
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True or false: DNA molecules are in an extended, uncondensed form called chromatin when the cell is not dividing.
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True or false: DNA can only replicate and transcribe when it is in the extended state.
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True or false: DNA molecules condense to form chromosomes during cell division.
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True or false: Spindle fibers are specialized microtubules that capture chromosomes during mitosis.
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True or false: Sister chromatids separate during anaphase of mitosis.
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True or false: Meiosis results in the production of four unique daughter cells.
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True or false: Lysosomes are vesicles filled with digestive enzymes used for intracellular digestion.
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True or false: The Golgi apparatus packages proteins in vesicles so that they may be excreted from the cell or used within the cell.
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True or false: Mitochondria have their own DNA and ribosomes that are similar in construction to prokaryotic ribosomes.
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True or false: Ribosomes are protein synthetic machinery made up of two subunits, each made of protein and ribosomal RNA (rRNA).
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True or false: Centrosomes contain centrioles, which are involved in the production of microtubules and help in cell division.
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True or false: Mitosis is the division of germ cells and results in two genetically identical daughter cells.
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True or false: Meiosis involves two fissions of the nucleus and gives rise to four sex cells, each possessing half the number of chromosomes of the original germ cell.
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True or false: Water is the most important inorganic compound found in cells?
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True or false: Nucleic acids are organic compounds found in cells?
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True or false: Mitosis is the division of somatic cells?
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True or false: Lysosomes are vesicles filled with digestive enzymes used for intracellular digestion?
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True or false: Sister chromatids separate during anaphase of mitosis?
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True or false: Repair enzymes help the cell recover from radiation-induced damage?
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True or false: Daughter cells produced in mitosis have the same number of chromosomes as the parent cell?
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True or false: Amino acids are natural monomers that form polymers when linked by peptide bonds.
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True or false: Enzymatic proteins function as organic catalysts, affecting the rate of chemical reactions without being altered themselves.
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True or false: Repair enzymes help the cell recover from a small amount of radiation-induced damage.
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True or false: Carbohydrates are chains of sugar molecules that primarily function as short-term energy sources.
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True or false: Nucleic acids are large complex macromolecules made from nucleotides.
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True or false: DNA molecules are tightly coiled to produce chromosomes, and every chromosome has a single DNA molecule.
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True or false: RNA acts as a messenger conveying instructions from DNA for controlling protein synthesis.
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True or false: The Golgi apparatus is functionally associated with the endoplasmic reticulum.
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True or false: The Golgi apparatus packages proteins in vesicles for excretion from the cell.
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True or false: Mitochondria have their own DNA and ribosomes that are similar in construction to prokaryotic ribosomes.
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True or false: Lysosomes are involved in intracellular digestion and can recycle cellular components.
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True or false: Ribosomes are the site of protein synthesis in the cell and can be found both free-floating in the cytoplasm and attached to the endoplasmic reticulum.
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True or false: Centrosomes contain centrioles, which are involved in cell division and the production of microtubules.
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True or false: Mitosis is the division of somatic cells and results in two genetically identical daughter cells.
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True or false: Mitosis is the division of somatic cells.
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True or false: Daughter cells produced in mitosis have the same number of chromosomes as the parent cell.
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True or false: Meiosis results in the production of four unique daughter cells.
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True or false: Meiosis involves two fissions of the nucleus and gives rise to four sex cells, each possessing half the number of chromosomes of the original germ cell.
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True or false: DNA molecules are in an extended, uncondensed form called chromatin when the cell is not dividing.
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True or false: DNA molecules condense to form chromosomes during cell division.
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True or false: Sister chromatids separate during anaphase of mitosis.
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True or false: The Golgi apparatus packages proteins in vesicles so that they may be excreted from the cell or used within the cell.
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True or false: Enzymatic proteins function as organic catalysts, affecting the rate of chemical reactions without being altered themselves.
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True or false: Cells are the building blocks of all living things.
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True or false: Protoplasm is responsible for the complex process of metabolism in cells.
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True or false: Water is the most important inorganic compound in cells.
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True or false: Proteins are the most important elementary building block of a cell.
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True or false: Carbohydrates primarily function as short-term energy sources in cells.
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True or false: Nucleic acids are organic compounds found in cells.
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True or false: Mitosis is the division of somatic cells.
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True or false: Proteins are made up of amino acids NH2 (amin) and COOH (carboxylic acid).
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True or false: Structural proteins provide the body with its shape and form, and are a source of heat and energy.
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True or false: Repair enzymes help the cell recover from a small amount of radiation-induced damage.
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True or false: Lipids are the most important elementary building block of a cell.
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True or false: RNA acts as a messenger conveying instructions from DNA for controlling protein synthesis.
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True or false: Enzymatic proteins function as organic catalysts, affecting the rate of chemical reactions without being altered themselves.
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True or false: Nucleic acids are large complex macromolecules made from nucleotides.
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True or false: The Golgi apparatus is functionally associated with the endoplasmic reticulum and packages proteins in vesicles for excretion from the cell or for use within the cell?
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True or false: Lysosomes are vesicles filled with digestive enzymes used for intracellular digestion?
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True or false: Mitochondria are the cellular powerhouses and are the site of much of the energy harvest by cells?
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True or false: Ribosomes are the site of protein synthesis in the cell and can be found both free-floating in the cytoplasm and attached to the endoplasmic reticulum?
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True or false: Centrosomes contain centrioles, which are involved in cell division and the production of microtubules?
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True or false: Daughter cells produced in mitosis have the same number of chromosomes as the parent cell?
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True or false: DNA molecules condense to form chromosomes during cell division?
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True or false: Mitosis is the division of somatic cells and results in two genetically identical daughter cells?
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True or false: Meiosis involves two fissions of the nucleus and gives rise to four sex cells, each possessing half the number of chromosomes of the original germ cell?
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True or false: In mitosis, chromosomes align along the equator of the cell during metaphase?
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True or false: During anaphase of mitosis, sister chromatids separate and are pulled towards opposite poles of the cell?
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True or false: Meiosis results in the production of four unique daughter cells, each with half the number of chromosomes as the original germ cell?
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True or false: In meiosis, there are two divisions of the nucleus: meiosis I and meiosis II?
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True or false: Meiosis is the process by which somatic cells divide and produce two identical daughter cells?
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True or false: Mitosis results in the production of four daughter cells, each with half the number of chromosomes as the original cell?
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True or false: Meiosis is a type of cell division that occurs in germ cells and results in the production of haploid daughter cells?
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Study Notes
Cell Basics
- A person contains approximately 100 trillion cells (1 x 10^14 cells)
- There are about 200 different cell types in mammals
- Cells are tiny, measuring about 0.002 cm (20 um) across
- Cells are the building blocks of living things
Cell Chemical Composition
- Cells are made of protoplasm
- Responsible for metabolism, reception and processing of food and oxygen, and elimination of waste products
- Composed of organic compounds (carbon, hydrogen, oxygen) and inorganic materials (no carbon)
- 24 elements form biomolecules, including 4 primary elements:
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
- When combined with phosphorus and sulfur, these elements form essential organic compounds:
- Proteins
- Carbohydrates
- Lipids
- Nucleic acids
Important Compounds
- Water: most abundant inorganic compound in cells
- Solvent for acids, bases, and salts
- Transports substances in and out of cells
- Maintains body temperature
- Cushions vital organs
- Lubricates digestive system and joints
- Organic compounds:
- Proteins: contain carbon, most important elementary building block of cells (15% of cell content)
- Carbohydrates: simple sugars, provide short-term energy
- Lipids: fatty acids, provide energy and structure
- Nucleic acids: DNA and RNA, carry genetic information
Proteins
- Types of proteins:
- Structural proteins: provide shape and form, source of heat and energy
- Enzymatic proteins: catalyze chemical reactions
- Repair enzymes: mend damaged molecules
- Functions of proteins:
- Hormones
- Antibodies
Nucleic Acids
- DNA (deoxyribonucleic acid):
- Long, tightly coiled into chromosomes
- 23 pairs of chromosomes in human cells
- Carries genetic information
- RNA (ribonucleic acid):
- Single-stranded structure
- Messenger RNA (mRNA) conveys instructions from DNA
- Transfer RNA (tRNA) carries amino acids to ribosomes
- Ribosomal RNA (rRNA) produces ribosomes
- Differences between DNA and RNA:
- DNA is double-stranded, RNA is single-stranded
- DNA contains deoxyribose, RNA contains ribose
- DNA has thymine, RNA has uracil
Cellular Structure
- Cell membrane:
- Made of lipid and proteins
- Controls passage of water and materials into and out of cell
- Nucleus:
- Surrounded by nuclear envelope
- Nuclear membrane has pores for entry and exit of materials
- Controls cellular activities
- Cytoplasm:
- Protoplasm outside the nucleus
- Functions: accepts and builds new substances, breaks down organic materials, packages substances for distribution
- Cytoplasmic organelles:
- Endoplasmic reticulum (ER): web-like structure for circulation, transport, and synthesis
- Golgi apparatus: packages proteins and lipids for transport
- Mitochondria: site of energy production
- Lysosomes: digest cellular waste and foreign substances
- Ribosomes: site of protein synthesis
- Centrosomes: involved in cell division
Cell Division
- Mitosis: somatic cell division, produces two identical daughter cells
- Interphase: cell growth and preparation
- Prophase: chromatin condenses, chromosomes form
- Metaphase: chromosomes align at cell equator
- Anaphase: sister chromatids separate
- Telophase: nuclear envelope reforms
- Cytokinesis: cytoplasm divides
- Meiosis: germ cell division, produces four unique daughter cells with half the number of chromosomes as the parent cell
Genetics
- Ploidy: number of sets of chromosomes in a cell
- Haploid (n): one set of chromosomes
- Diploid (2n): two sets of chromosomes
- Gametes (sperm or egg cells): haploid, contain 23 chromosomes
- Fertilization: fusion of gametes to form a diploid zygote (2n = 46)### Cell Structure and Function
- A cell is made up of protoplasm, which is responsible for metabolic processes, receiving and processing food and oxygen, and eliminating waste products.
- Protoplasm is composed of organic and inorganic compounds, with 4 primary elements: carbon, hydrogen, oxygen, and nitrogen.
- Organic compounds that make up the cell include:
- Proteins: contain the most carbon, are the building blocks of the cell, and provide shape and structure.
- Carbohydrates: provide short-term energy.
- Lipids: provide energy and insulation.
- Nucleic acids: store and replicate genetic information.
Cell Membrane
- The cell membrane is a lipid and protein bilayer that controls the passage of materials into and out of the cell.
- It acts as a barrier to protect the cell's contents and regulates the flow of materials.
Nucleus
- The nucleus is the cell's control center, surrounded by a double membrane called the nuclear envelope.
- Chromosomes are seen as threadlike structures when not condensed, but coil into visible structures during cell division.
- DNA is coiled around histone proteins to form chromatin.
Cytoplasm
- Cytoplasm is the protoplasm outside the nucleus, responsible for:
- Accepting and building up unrefined materials.
- Breaking down organic materials to produce energy.
- Packaging substances for distribution.
- Eliminating waste products.
Cytoplasmic Organelles
- Organelles are miniature cellular components that enable the cell to function in a highly organized manner.
- Types of organelles include:
- Endoplasmic reticulum (ER): involved in protein synthesis, transport, and storage.
- Golgi apparatus: packages proteins in vesicles for excretion or use within the cell.
- Mitochondria: site of energy harvesting, with its own DNA and ribosomes.
- Lysosomes: vesicles filled with digestive enzymes for intracellular digestion.
- Ribosomes: protein synthetic machinery.
- Centrosomes: involved in cell division and microtubule production.
Cell Division
-
Mitosis: division of somatic cells into two genetically identical daughter cells.
-
Meiosis: division of germ cells into four sex cells, each with half the number of chromosomes of the original cell.
-
Mitosis consists of 4 sub-phases:
- Prophase: chromatin condenses, chromosomes condense, and centrioles move apart.
- Metaphase: chromosomes align along the equator of the cell.
- Anaphase: sister chromatids separate, and spindle fibers pull chromatids towards the poles.
- Telophase: nuclear envelopes form around both groups of chromosomes, and chromosomes revert to their extended state.
-
Cytokinesis: the process of dividing the cell into two daughter cells.### Mitosis and Meiosis
-
Spindle fibers form from centrioles, capturing chromosomes and aligning them along the equator of the cell during metaphase.
-
In anaphase, sister chromatids separate, and spindle fibers shorten and pull chromatids towards the poles, while free spindle fibers lengthen and push the poles apart.
-
During telophase, spindle fibers disintegrate, nuclear envelopes form, and chromosomes revert to their extended state, followed by cytokinesis.
Meiosis
- Meiosis is a type of germ or sexual cell division that produces four unique daughter cells with half the number of chromosomes as the parent cell.
- Daughter cells are haploid, with one copy of each chromosome, designated as "n".
- Meiosis occurs in two divisions: meiosis I and meiosis II.
Ploidy and Genetics Terminology
- Ploidy refers to the number of sets of chromosomes in cells.
- Haploid cells have one set of chromosomes (n), while diploid cells have two sets of chromosomes (2n).
- In humans, gametes (sperm/ova) are haploid, with 23 chromosomes, while somatic cells are diploid, with 46 chromosomes.
Sexual Reproduction in Humans
- Fertilization results in a diploid zygote with 46 chromosomes, receiving 23 chromosomes from each parent.
- The combination of gametes from two parents with different genetic makeup results in unique offspring.
Meiosis vs. Mitosis
- Mitosis produces two diploid daughter cells with the same genetic information as the parent cell.
- Meiosis produces four haploid daughter cells with unique genetic information, different from the parent cell and each other.
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Test your knowledge of cell biology with this quiz! From the composition of cells to the different types found in mammals, challenge yourself to see how much you know about these microscopic building blocks of life.
