Chapter 2, achieve homework, notes, vocabulary Flashcards
Define prokaryote
Unicellular organism with a relatively simple cell structure
Define eukaryote
A compartmentalized cell structure with components bound by intracellular membranes; eukaryotes may be either unicellular or multicellular
Define bacteria
A type of prokaryote is also referred to as eubacteria or true bacteria.
Define archaea
A type of prokaryote is also referred to as ancient bacteria.
Define nucleus
A clear trait separates prokaryotic and eukaryotic cells when a nuclear membrane surrounds the genetic material.
Define histones
A special class of proteins that DNA wraps itself around to form chromosomes
Define chromatin
The complex of DNA and histone proteins
Define virus
Neither prokaryotic or eukaryotic, they are simple structures composed of an outer protein coat surrounding nucleic acid (either DNA or RNA)
Define homologous pair
When each chromosome in one set has a corresponding chromosome in the other set, together, they constitute this pair.
Define diploid
Cells that carry two sets of genetic information
Define haploid
Cells that carry a single set of chromosomes
Define polyploid
Cells that carry more than two sets of genetic information
Define centromere
A constricted region on the chromosomes, serves as attachment point for spindles
Define telomeres
Specific DNA sequences and associated proteins located at the tips of chromosomes
Define the origins of replication.
Sites where DNA synthesis begins
Define sister chromatids
Two initially identical copies of chromosome replicates
Define cell cycle
The series of stages through which a cell passes from one division to the next
Define checkpoints
Transition points throughout the cell cycle which allow or prohibit the cell’s progression to the next stage
Define interphase
The period between cell divisions in which the cell grows, develops, and functions.
Define M (mitotic) phase
The period of active cell division
Define mitosis
A part of the M phase, it is the process of nuclear division
Define cytokinesis
Cytoplasmic division
Define prophase
One of the stages in the M phase, it is when the chromosomes condense
Define condensins
A group of proteins that bind to the DNA within chromosomes and bring about condensation
Define prometaphase
One of the M (mitosis) phases it is when chromosomes become attached to microtubules from opposite spindle poles.
Define metaphase
Part of the M (mitosis) stage, is when chromosomes become arranged in a single plane.
Define anaphase
Part of the M (mitosis) stage, it is when chromosomes move toward opposite spindle poles
Define telophase
Part of the M (mitosis) stage, it is when the nuclear membrane re-forms around each set of chromosomes
Define meiosis
Sexual reproduction that leads to gametes in which the number of chromosomes is reduced by half
Define fertilization
When two haploid gametes fuse and restore the number of chromosomes to its original diploid value
Define prophase I
A lengthy stage in meiosis I in which the chromosomes form homologous pais and crossing over takes place
Define synapsis
The pairing of two chromosomes during meiosis
Define bivalent / tetrad
A homologous pair of synapsed chromosomes consisting of four chromatids
Define crossing over
Occurs in prophase I when homoelogous chromosomes exchange genetic information
Define metaphase I
When microtubules attach to opposite sides of chromosomes (to pull them apart)
Define anaphase I
When the two chromosomes of a homologous pair are pulled toward opposite poles
Define telophase I
When the chromosomes arrive at the spindle poles and the cytoplasm divides
Define interkinesis
The period between meiosis I and meiosis II, where the nuclear membrane re-forms around the chromosomes clustered at each pole
Define prophase II
Chromosomes recondense, spindle re-forms, and nuclear membrane once again breaks down
Define metaphase II
similar to metaphase of mitosis; the replicated chromosomes line up on the metaphase plate with sister chromatids facing opposite poles
Define anaphase II
Sister chromatids separate and are pulled to opposite poles
Define telophase II
Chromosomes arrive at the spindle, the nuclear membrane re-forms around chromosomes, and cytoplasm divides,for the second time
Define recombination
The creation of new combinations of alleles on a chromatid
Define cohesion
A protein that holds chromatids together
Define spermatogenesis
The production of gametes in male animals
Define spermatogonia
Diploid cells are produced by primordial germ cells dividing mitotically
Define primary spermatocyte
When a spermatogonium initiates meiosis and enters prophase I
Define secondary spermatocytes
When a primary spermatocyte competes meiosis I. These will then go on into meiosis II
Define spermatids
When secondary spermatocytes finish meiosis II, they will eventually develop into mature sperm.
Define oogenesis
The production of gametes in female animals
Define oogonia
Inside ovaries, the product of diploid primordial germ cells dividing mitotically
Define primary oocytes
When oogonia enter meiosis I and beging prophase I
Define secondary oocyte
When primary oocytes completes meiosis I and divides (cytoplasm is not shared equally between the two oocytes)
Define first polar body
One of the two haploid cells, which is smaller but contains half of the chromosomes and only a little cytoplasm
Define ovum
When a secondary oocyte completes meiosis II and cytokinesis is unequal, this is the larger cell that acquires most of the cytoplasm; the mature female gamete
Define second polar body
When a secondary oocyte ocmpletes meisosis II and cytokinesis is unequal, this is the smaller cell
What usually occurs to the first polar body and second polar body cells?
They usually disintegrate, only the ovum remains as the mature female gamete.
How much sperm are made from one “cycle”?
4
How much ovum are made from one “cycle”?
1
Define microsporocytes
Located in the stamen, they are male diploid reproductive cells
Define microspores
The product of microsporocytes undergoing meiosis, four of these are produced
Define megasporocytes
In plant, the female part of the flower, the ovary, contains these diploid cells (female reproduction site)
Define megaspores
The product of megasporocytes undergoing meiosis produces four of these
Categorize the following traits and which category they belong in.
Traits: Relatively small, typically less than 10 um in size; contains DNA; uses ribosome to synthesize proteins; nuclear membrane surrounds DNA; lacks a true cytoskeleton
Category: Prokaryotic cells, eukaryotic cells, both types of cells
Prokaryotic cells: Relatively small, typically less than 10 um in size; lack a true cytoskeleton
Eukaryotic: nuclear membrane surrounds DNA
Both cell types: Contain DNA, use ribosomes to synthesize proteins
A cell has circular chormome and histone proteins associated with its DNA, but lacks a nuclear membrane. Choose the domain of the cell with the best justification.
The cell belongs to Archaea because it has histone proteins, which are present in Archaea an Eukaryotes but absent in Eubacteria
What are the functions of mitotic cell division?
Asexual reproduction, cell regeneration, organism growth
Organize the phases of the cell cycle in the order of which they occur:
Cell division, G0 phase, G2phase, first stage of interphase, S phase
G0 phase, First stage of interphase, S phase, G2 phase, cell division
What are checkpoints?
Transition points during the cell cycle that ensure all cellular components are function properly
What does the G1/S checkpoint do?
Maintains cell until necessary enzymes for replication are synthesized
What does the G2/M checkpoint do?
Detection of DNA damage after replication
What does the spindle-assembly checkpoint do?
Ensures that cash chromosome is attached to spindle fibers from opposite poles
What are the stages of M phase?
Prophase, metaphase, anaphase, telophase, cytokinesis
Cell division by mitosis is a mechanism of asexual cell replication. Some single-celled organisms reproduce by cell division, and cell division enables multicellular organisms to grow and to repair damaged cells.
What is the product of cell division by mitosis?
Two cells genetically identical to the original cell
Identify the stages of meiosis.
- Chromosomes replicate in interphase
- Crossing over happens between non-sister chromatids f homologous pairs in prophase I
- Homologous pairs of chromosomes line up in metaphase I
- Homologous pairs split in anaphase I
- Telophase I and cytokinesis form two cells
- Spindle fibers reform in prophase II
- In metaphase II, duplicated chromosomes line up in the center of the cell
- Sister chromatids separate in anaphase II
- Telophase II and cytokinesis produce four cells
What happens during metaphase I of meiosis?
Homologous chromosomes are randomly arranged in the middle of the cell
What are the steps of oogenesis in human females?
- During fetal development, primordial germ cells in the ovaries undergo mitosis to generate diploid oogonia
- Diploid oogonia continue mitosis and produce primary oocytes before birth
- Primary oocytes are arrested at prophase I until puberty
- The completion of meiosis I results in one haploid secondary oocute and one haploid polat body
- Secondary oocytes are released into the fallopian tube at ovulation and arrest at metaphase II
- If fertilized by a sperm cell, the secondary oocyte will complete meiosis II, generating a fertilized diploid egg and an additional haploid polar body
