The Biological Basis of Life Flashcards
What are the mechanisms of life that Evolution is grounded in? (4)
(…genetic information, transmission…)
- Cells
- Cell Replication
- Replication and decoding of genetic information
- Transmission of this information between generations
Why do cells and DNA matter?
To examine how life is organized at the cellular and molecular level
Cytology
The branch of science that specializes in cell biology
Cytologenetics
Study of the hereditary mechanisms within cells
Cell
Basic unit of life in all organisms
(Smallest entities capable of self-reproduction)
Prokaryotes
Single-celled organisms
When did Prokaryotes first appear on Earth
3.7 billion years ago
Prokaryotes are enclosed by a _____
plasma membrane
Prokaryotes have no _____ and _____
membrane around the nucleus and no membranous organelles
In Prokaryotes, genetic information is in direct contact with the ______
Cytoplasm
Cytoplasm
The fluid-filled space within the cell
Eukaryotes
More complex cells (including fungi, plants, animals, and humans)
When did Eukaryotes first appear on Earth?
1.2 billion years ago
Special Characterstic of the Cell Membrane in Eukaryotes
(Active component of cellular function) Controls the exchange of materials with external environment
Cell Coat Characteristics (2)
- Consists of glycoproteins and polysaccarides
- Provide the cell with its biochemical identity
Nucleus Characteristics (3)
- One of the most important organelles
- Bound by a membrane in Eukaryotic cells
- Contains DNA
Function of Organelles
Divide the cell into a number of functional compartments
Endoplasmic Reticulum (ER) (2)
(network of…, site of…)
- Network of membranous channels in the cytoplasm
*looks like folded sheets - Site of protein synthesis
Ribosomes (2)
(comprised of what?)
- Comprised of RNA
- Studded on outer surface of ER
Golgi Apparatus (3)
(what is it made of, …proteins, source of…)
- Clusters of flattened membrane sacs
- Modify + distribute proteins synthesized by the ER
- Source of membranes for other organelles
Mitochondria
Produces energy in the cell by converting energy in food into ATP (main fuel of cells)
Protein membrane around mitochondria
Proteins produced by DNA
Centrioles
Important for organization of spindle fibers that function in cellular division
Where are centrioles found?
In specialized region of cytoplasm called the Centrosome
Somatic Cells
Make up the cellular composition of the body
Sex Cells (Gametes)
Cells specifically involved in reproduction
Gamete Function (2)
- To unite with a sex cell from another individual to form a zygote
- transmit genetic information from parent to offspring
2 Types of Gametes
- Ova (eggs)
- Sperm
Cell Division
The process that results in production of new cells
Cell Cycle
The sequence of events from one division to another
Interphase
when ________ processes occur
- The period between cell division
- When basic metabolic processes and other activities occur
*much of the cell’s existence is spent in this phase
3 Phases of Interphase
- G1 phase
- S phase
- G2 phase
Gap 1 (G1) Phase
Begins immediately after a division
G1 Characteristics (3)
- Cell’s DNA exists as chromatin
- Cell size doubles
- Cell replaces cellular organelles lost during division
Chromatin
uncoiled, long strands of DNA
S Phase
DNA/chromatin is duplicated
G2 Phase
Period of Growth
When does the cell undergo cell division?
At the end of G2 phase
Mitosis
Somatic Cell Division
Mitosis Characteristics (2)
- “Simple” Cell division
- Divides once to produce 2 daughter cells
Daughter Cells
Genetically identical to each other and the original cell
Diploid
Complement of chromosomes in humans (46)
4 Phases of Mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
Prophase Characteristics (4)
- Chromosomes coil and become visible
- Duplicated chromosomes join at the centromere
- Nuclear membranes begin to breakdown
- Centrioles move to opposite sides of the cell
Metaphase Characteristics (3)
(something disappears, movement, attachment)
- Begins when nuclear membrane fully disappears
- Chromosomes align at the equator of the cell
- Spindle fibers attach at the centromeres
Anaphase Characteristics (3)
- Spindle fibers contract
- Duplicated chromosomes split at the centromere
- Identical chromosomes move to opposite sides of the cell
Telophase Characteristics (4)
- Spindle fibers break down
- The ER forms 2 new nuclear membranes
- Chromosomes uncoil and become chromatin
- Cell divides into 2 genetically identical daughter cells
Meiosis
Leads to the development of new individuals by producing reproductive cells or gametes
Where does Meiosis occur specifically?
In the testes of males and the ovaries of females
Result of Meiosis
2 Divisions that result in 4 daughter cells that each half 23 chromosomes
Haploid
Half the number of chromosomes in humans (23)
Meiosis Phases (8)
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II
Prophase I Characteristics (4)
- Chromosomes coil and become visible
- Duplicated chromosome join at the centromere
- Nuclear membrane begins to break down
- Centrioles move to opposite sides of the cell
Recombination (crossing over)
Exchange of genetic information between homologous chromosomes
Homologous chromosomes
A set of maternal and paternal chromosomes that pair up with each other during fertilization
Metaphase I Characteristics (3)
- Begins when nuclear membrane fully disappears
- Chromosomes align at cell equator
- Spindle fibers attach to centromeres
Anaphase I Characteristics (3)
- Spindle fibers contract and make duplicated chromosomes split at the centromere
- Identical chromosomes migrate to opposite sides of the cell
- Complete set of chromosomes at each pole of the cell
Telophase I Characteristics (4)
- Spindle fibers break down
- The ER forms 2 new nuclear membranes
- Chromosomes uncoil and become chromatin
- Cell divides into 2 cells
Prophase II Characteristics (2)
- Centrioles move to opposite sides of the cell
- Nuclear membranes begin to disappear around both nuclei
Metaphase II Characteristics (3)
- Nuclear membrane disappears
- Chromosomes align on cell equator
- Spindle fibers attach to the centromeres of each chromosome
Anaphase II Characteristics (2)
- Spindle fibers contract splitting the centromeres (separate homologous chromosomes)
- Homologous chromosomes move to opposite poles
Telophase II Characteristics (3)
- Haploid sets of daughter chromosomes are at opposite poles
- Nuclear membranes re-form
- Cells undergo second meiotic division
Final result of Meiosis
4 Haploid daughter cells, each with one copy of each chromosomes
Gametogenesis
Meiosis of cells that result in formation of ova and spermatozoa
Spermatogenesis
Meiotic process in male testes
Spermatogenesis Characteristics (2)
- Spermatogonia (germ cells) produce daughter cells (called spermatocytes)
- Spermatocytes undergo meiosis to produce 4 haploid cells (called spermatids)
How long does Spermatogenesis last?
48 Days:
- 16 for Meiosis I
- 16 for Meiosis II
- 16 for conversion into mature sperm
Oogenesis
Production of gametes in the ovaries
Oogonia
(____ that produce through ____)
Germ cells that divide by meiosis to produce primary oocytes
What does the first meiotic division produce in Oogenesis?
(hint: 2 things)
Primary oocyte and Polar Body
Primary Oocyte
(what does it contain?)
large cell that contains 95% of cytoplasm
Polar Body
Other smaller cell
What does the second meiotic division produce in Oogenesis?
(hint: 4 things)
Ovum and 3 polar bodies
What is unique about the polar bodies at the end of the 2nd meiotic division in Oogenesis?
They have almost no cytoplasm and cannot function as gametes
Karyotype
All the chromosomes in a cell that are examined through a photograph
How are chromosomes organized in a Karyotype
By chromosome size and centromere location
4 Classes of Chromosomes
(____tric)
- Metacentric
- Submetric
- Acrocentric
- Teleocentric
Metacentric Chromosome
Centromere is approximately in the center
Submetric Chromosome
Centromere to one side of chromosome center
*arms of unequal length
Acrocentric Chromosomes
Centromere near one end
*arms of very unequal length
Teleocentric Chromosomes
Centromere at the very tip of chromosomes
*not present in human karyotype
Short arm
p arm (petite arm)
Long Arm
q arm