Cell Biology Module 3: Organelles and Cell Division

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Questions and Answers

What is the result of mitosis?

Two genetically identical daughter cells (correct)

Four genetically identical daughter cells

One genetically identical daughter cell

Four genetically different daughter cells

During which stage of mitosis do chromosomes condense and become visible?

Telophase

Anaphase

Metaphase

Prophase (correct)

What is the primary function of cytokinesis?

To divide the nucleus into two identical parts

To divide the cytoplasm into two separate daughter cells (correct)

To separate sister chromatids

To replicate chromosomes

What is unique about meiosis I compared to mitosis?

Synapsis and crossing over occur Signup and view all the answers

What is the result of meiosis?

Four gametes with half the number of chromosomes Signup and view all the answers

During which stage of meiosis I do homologous chromosomes line up in the cell center?

Metaphase I Signup and view all the answers

What is the purpose of crossing over during meiosis?

To create genetic variation Signup and view all the answers

During which stage of meiosis II do sister chromatids move to opposite poles?

Anaphase II Signup and view all the answers

What is the outcome of Meiosis II?

Four haploid cells, each with one copy of each chromosome Signup and view all the answers

What is the definition of genetics?

The study of heredity and variation Signup and view all the answers

What is the purpose of synapsis in meiosis?

To pair homologous chromosomes Signup and view all the answers

What is the result of crossing over in meiosis?

The exchange of genetic material between homologous chromosomes Signup and view all the answers

What is the process of cell division that produces gametes with half the number of chromosomes?

Meiosis Signup and view all the answers

What is the reason for Mendel's use of pea plants in his experiments?

They are easy to cultivate and have a short generation time Signup and view all the answers

What is the term for the division of the cytoplasm?

Cytokinesis Signup and view all the answers

What is the result of the telophase II stage of meiosis?

The nuclear envelope reforms around daughter chromosomes Signup and view all the answers

Which type of bacteria is characterized by being anaerobic and having unique DNA in their ribosomes?

Eubacteria Signup and view all the answers

What is the purpose of scientific nomenclature in biology?

All of the above Signup and view all the answers

What is the term for the study of the classification and naming of living organisms?

Taxonomy Signup and view all the answers

What is the basic unit of structure and function in living things?

Cell Signup and view all the answers

What is the term for a group of cells that perform a single function?

Tissue Signup and view all the answers

Which type of bacteria is found in extreme environments?

Archaebacteria Signup and view all the answers

What is the abbreviation used to refer to unknown species?

sp. Signup and view all the answers

What is the purpose of classification in biology?

To organize and understand the vast diversity of life Signup and view all the answers

What is the primary function of the endoplasmic reticulum?

Protein synthesis Signup and view all the answers

During which stage of the cell cycle does the cell's copied DNA get distributed into each daughter cell?

Mitosis Signup and view all the answers

What is the result of the cell cycle?

Two identical daughter cells Signup and view all the answers

What is the function of the G2 phase of interphase?

Preparing for cell division Signup and view all the answers

What is the term for the indistinguishable mass of DNA and proteins?

Chromatin Signup and view all the answers

During which phase of interphase does the cell make a copy of its DNA?

S phase Signup and view all the answers

What is the function of the Golgi apparatus?

Protein processing Signup and view all the answers

How many pairs of homologous chromosomes do human somatic cells have?

23 pairs Signup and view all the answers

What is the primary function of the nervous system?

To recognize and coordinate the body's response to changes in internal and external environments Signup and view all the answers

What is the main difference between sensory neurons and motor neurons?

Sensory neurons carry impulses from sense organs to the spinal cord and brain, while motor neurons carry impulses from the brain and spinal cord to muscles and glands Signup and view all the answers

What is the approximate number of neurons in the human brain?

100 billion Signup and view all the answers

What is the main function of the central nervous system (CNS)?

To relay, process, and analyze information Signup and view all the answers

What is the term for the electrical signals transmitted by neurons?

Impulses Signup and view all the answers

What is the main function of interneurons?

To connect sensory and motor neurons and carry impulses between them Signup and view all the answers

What is the term for a group of different types of tissues that work together to perform a single function?

Organ Signup and view all the answers

How many organ systems are there in the human body?

11 Signup and view all the answers

Study Notes

Organelles

Membrane-bound structures within cells performing specific functions
Includes mitochondria (energy production), endoplasmic reticulum (protein synthesis), and Golgi apparatus (protein processing)

Cell Division

Essential for reproduction, growth, and repair
Involves splitting a single cell into new cells, distributing genetic information from parent cells to daughter cells

The Cell Cycle

Regular sequence of growth and division that eukaryotic cells undergo
Divided into three main stages: Interphase, Mitosis, and Cytokinesis

Interphase

Cell grows, makes a copy of its DNA, and prepares for division
Consists of three parts: G1 (Growth Phase), S (DNA Copying Phase), and G2 (Preparation Phase)

Chromosomes and Chromatids

Human somatic cells have 23 pairs of homologous chromosomes, one from each parent
Chromatin (DNA and proteins) condenses into chromosomes during the S phase of interphase, forming an "X" shape
Each chromosome consists of two identical sister chromatids attached by a centromere

Chromosome Structure

Chromatin: Indistinguishable mass of DNA and proteins
Chromatids: Identical parts of a chromosome attached by a centromere

Mitosis

Results in two genetically identical daughter cells
Divided into four stages: Prophase, Metaphase, Anaphase, and Telophase

Cytokinesis

Division of the cytoplasm, resulting in two separate daughter cells with identical nuclei

Meiosis

Process of cell division producing four gametes with half the number of chromosomes
Consists of two rounds of division: Meiosis I and Meiosis II

Unique Features of Meiosis

Synapsis: Homologous chromosomes pair along their length after replication
Crossing Over: Exchange of genetic material between homologous chromosomes during synapsis, causing genetic variation
Reduction Division: Chromosomes are not copied between divisions, resulting in haploid cells

Meiosis I

Prophase I: Chromosomes become visible, homologous chromosomes pair, and crossing over occurs
Metaphase I: Homologous chromosomes line up in the cell center
Anaphase I: Spindle fibers shorten, separating homologous chromosomes (sister chromatids remain paired)
Telophase I: Nuclear membrane reforms, resulting in two haploid cells, each with two sister chromatids

Meiosis II

Prophase II: Nuclear membrane breaks down again
Metaphase II: Chromosomes line up in the cell center
Anaphase II: Spindle fibers shorten, and sister chromatids move to opposite poles
Telophase II: Nuclear envelope reforms around daughter chromosomes

End of Meiosis II

Results in four haploid cells, each with one copy of each chromosome (23 chromosomes in humans)

Key Terms

Cell Cycle: Sequence of growth and division in eukaryotic cells
Interphase: Phase of growth and DNA replication
Mitosis: Division of genetic material into two daughter cells
Cytokinesis: Division of the cytoplasm
Meiosis: Division process producing gametes with half the chromosomes
Synapsis: Pairing of homologous chromosomes
Crossing Over: Exchange of genetic material between homologous chromosomes
Reduction Division: Division resulting in haploid cells

Genetics

Definition: Study of heredity and variation, investigating how genes and traits are passed from parents to offspring
Genetic Information: Located in the cell nucleus, cells undergo division and reproduction, passing genes from parents to offspring

Gregor Mendel's Experiment

Foundation: Mendel's experiments with garden pea plants established the basic rules of inheritance
Reasons for Using Pea Plants: Small and easy to cultivate, short generation time, ability to self-fertilize and cross-pollinate, and seven distinct contrasting traits

Characteristics of Pea Plants

Traits: Stem height, seed shape, seed color, flower color, pod shape, pod color, and flower position
Dominant and recessive traits: Tall and short, round and wrinkled, yellow and green, purple and white, inflated and constricted, green and yellow, and axial and terminal

Mendel's Experiment Process

Purebred Plants: Produced purebred plants (P1 generation) with specific traits
Cross-pollination: Pollen from one plant fertilized the eggs of another plant
F1 Generation: Resulting offspring from cross-pollination
F2 Generation: Resulting offspring from self-pollination of F1 generation

Archaebacteria

Found in extreme environments (hot boiling water, thermal vents, acidic conditions with no oxygen)
Anaerobic, with unique DNA in their ribosomes
Includes methanogens, thermophiles, and halophiles

Eubacteria

Diverse in shape, chemical composition, nutritional requirements, and biochemical activities
Important decomposers in the ecosystem, recycling nutrients

Scientific Nomenclature

Rules for Scientific Names: Organisms are identified by their binomial name (genus and species), genus name is capitalized, and species name is not
Importance of Scientific Names: Provides useful information about evolutionary history and relationships, acts as shorthand for describing plants or animals, and developed using Latin and Greek

Cells

Basic unit of structure and function in living things
In multicellular organisms, cells are often specialized, each uniquely suited to perform specific functions

Tissues

Group of cells that perform a single function
Four basic types of tissue in the human body: Epithelial, Connective, Nervous, and Muscle tissue

Organs

Group of different types of tissues that work together to perform a single function
Example: The eye is an organ composed of epithelial, nervous, muscle, and connective tissues, all working together to enable sight

Organ Systems

Group of organs that perform closely related functions
Eleven organ systems of the human body work together to maintain homeostasis

Nervous System

Recognizes and coordinates the body's response to changes in internal and external environments
Structures: Brain, Spinal cord, and Peripheral nerves
Divisions: Central Nervous System (CNS) and Peripheral Nervous System (PNS)
CNS: Acts as the control center of the body, relays, processes, and analyzes information
Brain: Has approximately 100 billion neurons and weighs about 1.4 kilograms

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Description

Learn about the membrane-bound structures within cells, their functions, and the process of cell division, including the distribution of genetic information from parent to daughter cells.