NSCL Unit 2

Chapters 6, 7, & 8

genome

the entire genetic complement (DNA) of an organism

diploid

describes a cell, nucleus, or organism containing two sets of chromosomes (2n)

haploid

describes a cell, nucleus, or organism containing one set of chromosomes (n)

gamete

a haploid reproductive cell or sex cell (sperm or egg)

haploid

describes a cell, nucleus, or organism containing one set of chromosomes. (n)

diploid

describes a cell, nucleus, or organism containing two sets of chromosomes (2n)

gamete

a haploid reproductive cell or sex cell (sperm or egg)

homologous chromosomes

chromosomes of the same length with genes in the same location; diploid organisms have pairs of this, and the members of each pair come from different parents

gene

the physical and functional unit of heredity; a sequence of DNA that codes for a specific peptide of RNA molecule

locus

the position of a gene on a chromosome

cell cycle

the ordered sequence of events that a cell passes through between one cell division and the next

interphase

the period of the cell cycle leading up to mitosis; includes G1, S, and G2 phases; the interim between two consecutive cell divisions

mitotic phase

the period of the cell cycle when duplicated chromosomes are distributed into two nuclei and the cytoplasmic contents are divided; includes mitosis and cytokinesis

G1 phase

(also, first gap) a cell-cycle phase; first phase of interphase centered on cell growth during mitosis

S Phase

the second, or synthesis phase, of interphase, during which DNA replication occurs

centriole

a paired rod-like structure constructed of microtubules at the center of each animal cell centrosome

mitotic spindle

the microtubule apparatus that orchestrates the movement of chromosomes during mitosis

G2 phase

(also, second gap) a cell-cycle phase; third phase of interphase where the cell undergoes the final preparations for mitosis

mitosis

the period of the cell cycle at which the duplicated chromosomes are separated into identical nuclei; includes prophase, prometaphase, metaphase, anaphase, and telophase

prophase

the stage of mitosis during which chromosomes condense and the mitotic spindle begins to form

prometaphase

the stage of mitosis during which mitotic spindle fibers attach to kinetochores

kinetochore

a protein structure in the centromere of each sister chromatid that attracts and binds spindle microtubules during prometaphase

metaphase

the stage of mitosis during which chromosomes are lined up at the metaphase plate

metaphase plate

the equatorial plane midway between two poles of a cell where the chromosomes align during metaphase

anaphase

the stage of mitosis during which sister chromatids are separated from each other

telophase

the stage of mitosis during which chromosomes arrive at opposite poles, decondense, and are surrounded by new nuclear envelopes

cytokinesis

the division of the cytoplasm following mitosis to form two daughter cells

cleavage furrow

a constriction formed by the action ring during animal-cell cytokinesis that leads to cytoplasmic division

cell plate

a structure formed during plant-cell cytokinesis by Golgi vesicle fusing at the metaphase plate; will ultimately lead to formation of a cell wall to separate the two daughter cells

S phase

Chromosomes are duplicated during what portion of the cell cycle?

G0 phase

a cell-cycle phase distinct from the G1 phase of interphase; a cell in this phase is not preparing to divide

quiescent

describes a cell that is performing normal cell functions and has not initiated preparations for cell divisions

cell cycle checkpoints

mechanisms that monitor the preparedness of a eukaryotic cell to advance through the various cell cycle stages

G1 checkpoint

checkpoint for cell size, protein reserves, and genomic damage

G2 checkpoint

checkpoint for cell size, protein reserves, all chromosomal replication and no damage to replicated chromosomes

M checkpoint

sister chromatids attached to microtubules

proto-oncogene

a normal gene that controls cell division by regulating the cell cycle that becomes an oncogene if it is mutated

oncogene

a mutated version of a proto-oncogene, which allows for uncontrolled progression of the cell cycle, or uncontrolled cell reproduction

tumor suppressor gene

a gene that codes for regulator proteins that prevent the cell from undergoing uncontrolled division

binary fission

the process of prokaryotic cell division

origin

the region of the prokaryotic chromosome at which replication begins

septum

a wall formed between bacterial daughter cells as a precursor to cell separation

FtsZ

a tubulin-like protein component of the prokaryotic cytoskeleton that is important in prokaryotic cytokinesis

genes

An organism’s traits are determined by the specific combination of inherited____

anaphase

Separation of the sister chromatids is a characteristic of which stage of mitosis?

accurate and complete DNA replication

What is the most important role of the G2 checkpoint?

proto-oncogene

a gene that codes for a positive cell cycle regulator is called___

mitosis

Which eukaryotic cell-cycle event is missing in binary fission?

Interphase-Prophase-Prometaphase-Metaphase-Anaphase-Telophase

The correct sequence of the major phases of mitosis

meiosis

a nuclear division process that results in four haploid cells

life cycle

the sequence of events in the development of an organism and the production of cells that produce offspring

haploid-dominant

a life-cycle type in which the multicellular haploid stage is prevalent

diploid-dominant

a life-cycle type in which the multicellular diploid stage is prevalent

alternation of generations

a life-cycle type in which the diploid and haploid stages alternate

germ cell

a specialized cell that produces gametes, such as eggs or sperms

gametophyte

a multicellular haploid life-cycle stage that produces gametes

sporophyte

a multicellular diploid life-cycle stage that produces spores

alternation of generations

What type of life cycle has both haploid and diploid multicellular stages?

fertilization

the union of two haploid cells typically from two individual organisms

somatic cell

all the cells of a multicellular organism except the gamete-forming cells

meiosis I

the first round of meiotic cell division; referred to as reduction division because the resulting cells are haploid

meiosis II

the second round of meiotic cell division following meiosis I; sister chromatids are separated from each other, and the result is four unique haploid cells

• from previous mitotic division a cell has diploid 2N chromosomes and tetraploid 4N DNA

• From that DNA, copies of the chromosome are formed

• the copies are referred to as homologous dyads aka “sister chromatids”

before meiosis

synapsis

the formation of a close association between homologous chromosomes during prophase I

crossing over (recombination)

the exchange of genetic material between homologous chromosomes resulting in chromosomes that incorporate genes from both parents of the organism forming reproductive cells

chiasmata

the structure that forms at the crossover points after genetic material is exchanged

tetrad

two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase I)

recombinant

describing something composed of genetic material from two sources, such as a chromosome with both maternal and paternal segments of DNA

Prophase I

What phase of meiosis?

• dyad pairs align to create tetrads

• during a process called crossing-over: non-sister chromatids trades sections at a chiasma

Prometaphase I

spindle fiber microtubules attach to chromosomes

Metaphase I

• chromosomes connect via spindle fibers from a kinetochore to one pole of the cell

• homologous chromosomes align at the cell equator

• each homologous chromosome is RANDOMLY aligned with one pole or the other

anaphase I

• chiasmata break apart

• homologous chromosomes migrate towards opposite poles

telophase I

• chromosomes arrive on opposite sides of the cell

• cleavage furrow forms

cytokinesis I

• the cell is split into two

• each with one chromosome set therefore haploid (despite two copies as sister chromatids)

• sister chromatids are no longer identical copies because of crossing-over

reduction division

a nuclear division that produces daughter nuclei each having one-having as many chromosome sets as the parental nucleus; meiosis I is an example of this

interkinesis

a period of rest that may occur between meiosis I and meiosis II; there is no replication of DNA during interkinesis

prophase II

new spindles begin to form

prometaphase II

spindle fiber microtubules attach to the individual kinetochores of sister chromatids

metaphase II

• sister chromatids are attached by microtubules to opposite poles

• sister chromatids are aligned in the center of the cells

anaphase II

• sister chromatids are pulled apart by spindle fibers

• sister chromatids move toward opposite ends of the cell

telophase II

• chromosomes arrive on opposite sides of the cell

• cleavage furrow forms

• nuclear envelopes form

cytokinesis II

• separated 2 cells into 4 haploid cells

• each cell has one copy of a complete set of chromosomes

• each cell is genetically unique

anaphase II

At what stage of meiosis are sister chromatids separated from each other?

karyotype

the number and appearance of an individuals chromosomes, including the size, banding patterns, and centromere position

karyogram

the photographic image of karyotype

translocation

the process by which one segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome

chromosome inversion

the detachment, 180° rotation, and reinsertion of a chromosome arm

nondisjunction

the failure of synapsed homologs to completely separate and migrate to separated poles during the first cell division of meiosis

euploid

an individual with the appropriate number of chromosomes for their species

autosome

any of the non-sex chromosomes

aneuploid

an individual with an error in chromosome number; includes deletions and duplications of chromosome segments

monosomy

an otherwise diploid genotype in which one chromosome is missing

trisomy

an otherwise diploid genotype in which one entire chromosome is duplicated

x inactivation

the condensation of X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose

polyploid

an individual with an incorrect number of chromosome sets

sexual reproduction results in greater variation in the offspring

What is a likely evolutionary advantage of sexual reproduction over asexual reproduction?

Four haploid

Meiosis produces _______ daughter cells

meiosis II

The part of meiosis that is similar to mitosis

16

If a muscle cell of a typical organism has 32 chromosomes, how many chromosomes will be in a gamete of that same organism?

X inactivation

Abnormalities in the number of X chromosomes tend to be milder than the same abnormalities in autosomes because of _____