40 Questions
What is the result of mitosis?
Two genetically identical daughter cells
During which stage of mitosis do chromosomes condense and become visible?
Prophase
What is the primary function of cytokinesis?
To divide the cytoplasm into two separate daughter cells
What is unique about meiosis I compared to mitosis?
Synapsis and crossing over occur
What is the result of meiosis?
Four gametes with half the number of chromosomes
During which stage of meiosis I do homologous chromosomes line up in the cell center?
Metaphase I
What is the purpose of crossing over during meiosis?
To create genetic variation
During which stage of meiosis II do sister chromatids move to opposite poles?
Anaphase II
What is the outcome of Meiosis II?
Four haploid cells, each with one copy of each chromosome
What is the definition of genetics?
The study of heredity and variation
What is the purpose of synapsis in meiosis?
To pair homologous chromosomes
What is the result of crossing over in meiosis?
The exchange of genetic material between homologous chromosomes
What is the process of cell division that produces gametes with half the number of chromosomes?
Meiosis
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
What is the term for the division of the cytoplasm?
Cytokinesis
What is the result of the telophase II stage of meiosis?
The nuclear envelope reforms around daughter chromosomes
Which type of bacteria is characterized by being anaerobic and having unique DNA in their ribosomes?
Eubacteria
What is the purpose of scientific nomenclature in biology?
All of the above
What is the term for the study of the classification and naming of living organisms?
Taxonomy
What is the basic unit of structure and function in living things?
Cell
What is the term for a group of cells that perform a single function?
Tissue
Which type of bacteria is found in extreme environments?
Archaebacteria
What is the abbreviation used to refer to unknown species?
sp.
What is the purpose of classification in biology?
To organize and understand the vast diversity of life
What is the primary function of the endoplasmic reticulum?
Protein synthesis
During which stage of the cell cycle does the cell's copied DNA get distributed into each daughter cell?
Mitosis
What is the result of the cell cycle?
Two identical daughter cells
What is the function of the G2 phase of interphase?
Preparing for cell division
What is the term for the indistinguishable mass of DNA and proteins?
Chromatin
During which phase of interphase does the cell make a copy of its DNA?
S phase
What is the function of the Golgi apparatus?
Protein processing
How many pairs of homologous chromosomes do human somatic cells have?
23 pairs
What is the primary function of the nervous system?
To recognize and coordinate the body's response to changes in internal and external environments
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
What is the approximate number of neurons in the human brain?
100 billion
What is the main function of the central nervous system (CNS)?
To relay, process, and analyze information
What is the term for the electrical signals transmitted by neurons?
Impulses
What is the main function of interneurons?
To connect sensory and motor neurons and carry impulses between them
What is the term for a group of different types of tissues that work together to perform a single function?
Organ
How many organ systems are there in the human body?
11
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
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.
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