Meiosis 2 Flashcards

Terms Definitions
make gametes
meiosis
Telophase II
egg
the female gamete
Anaphase II
Centromeres split.
nondisjunction leads to __________
aneuploidy
haploid
single set of chromosomes
Meiosis I
seperates homologous chromosomes, cutting the number in half
Variation
Offspring differ somewhat in appearance from parents and siblings.
duplication
An aberration in chromosome structure resulting from an error in meiosis or mutagens; duplication of a portion of a chromosome resulting from fusion with a fragment from a homologous chromosome.
inversion
An aberration in chromosome structure resulting from an error in meiosis or from mutagens; specifically, reattachment of a chromosomal fragment to the chromosome from which the fragment originated, but in a reverse orientation.
centromere
The centralized region joining two sister chromatids
Prophase I
chromosomes condense, nuclear membrane disapears, centrosomes move (same as mitosis!)
 
synapsis occurs; joining the homologous chromsomes producing tetrads
 
two chrom. can exchange fragments through crossing over
two types of reproduction
asexual and sexual
these cells:replace old dead skin cells
mitosis
Deletion
loss of a piece of chromosome
Cytokinesis I
Occurs simultaneously with telophase I
crossing over
Nonsister chromatids exchange genetic information.
Zygote
The resulting fertilized egg, from fertilization, that contains the two haploid sets of chromosomes bearing genes representing the maternal and paternal family lines.
Prophase 1
Each chromosome seaks out corrisponding homologous chromosome to form Tetrad. Matching up crossing-over = new combo of genes
cytological maps
Charts of chromosomes that locate genes with respect to chromosomal features.
wild type
An individual with the normal phenotype.
Mitosis
A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. It conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei.
Anaphase
Diads are pulled apart by spindle fibers which use the protien dynein. This protien uses ATP to pull.
Variation in Meiosis
Crossing over and Indpendent Assortment
 
Crossing Over: genes assorted (some from each parent)
 
Ind. Assortment:chromosome randomly selected for gamete formation
add roots and shoots from plant cuttings
mitosis
Insertion or addition
extra DNA inserted or added
Telophase I
Cytoplasm divides, forming two new daughter cells
Anaphase I
Homologous pairs are pulled to opposite poles of the cell.
Chiasmata
Also visable in the light microscope are X-shaped regions called chiasmata.
Telophase II-
-nuclei re-form -the spindles break down -the cytoplasm divides -identical to mitosis (Meiosis II)
spermatogenesis
the process by which male gametes form
somatic cell
Any cell in a multicellular organism except a sperm or egg cell.
genomic imprinting
The parental effect on gene expression whereby identical alleles have different effects on offspring, depending on whether they arrive in the zygote via the ovum or via the sperm.
meiosis
A two-stage type of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
A haploid sperm joins with an egg generating a zygote, the cells of the zygote would be _______________.
Diploid
Are the daughter cells genetically identical to each other and the parents cells in meiosis? mitosis?
meiosis-they have variations....mitosis, they are the same
the nucleus divides multiple times before cytoplasm is divided, example?
multiple fission, malaria
Beneficial effect
enhance fitness (ability to pass good or bad things)
Metaphase II
Chromsomes (not tetrads) line up in the middle of the cell
Telophase 1:
-the spindle breaks down and the chromosomes uncoil -the cytoplasm divides to yield two new cells -each cell has half the genetic information of the original cell because it has only one homo- logous chromosome from each pair
polar body
a short-lived product of the formation of gametes by meiosis
Diploid
A cell with two of each kind of chromosomes.
allele
One of two or more molecular forms of a gene that arise by mutation and specify slightly different versions of the same trait.
animals with both male and female organs...examples?
hermaphroditism; earthworms, flatworms
How many useable haploid cells does Spermatogenesis produce?
4 sperm cells
Diploid cells
The zygote and all other cells having two sets of chromosomes.
Meiosis Stages?
2 Meiosis stages (remember the S phase DNA replication)
 
the formation of a new individual from a clump of cells surrounded by a resistant capsule aka a gemmule....example?
gemmulation, freshwater sponges
Trisomy 21– Downs Syndrome
an extra chromosome on the 21st chromosome pair.
Describe the telophase I of MEIOSIS
1. cytokinesis occurs completing the first division cycle of meiosis
Conjugation - in simple organisms
1. Cytoplasm bridge forms between 2 cells and an exchange of DNA takes place2. Occurs between two cells with different mating types3. Mating types are usually called plus (+) and minus (-)
List 2 characteristics of the metaphase for cells undergoing MITOSIS. Remember the prefix "meta" means middle, or semi, so this is the middle of Mitosis
1. alignment of chromosomes along the equatorial plane.2. replication of the centromeres.
What makes Meiosis II different from I?
the chromosomes do not replicate before dividing at centromeres, the identical chromatids seperate
Crossing over; what is it and when does it occur?
exchange of genetic material between homologues during prophase 1
 
produces genetic recombination
The end products of Meiosis are:
Sperm: 4 haploid Eggs: 4 haploid, one viable the other three are absorbed into the body.
meiosis 1
reduction
down's syndrome
extra 21st chromosome
spermatid
matures into a male gamete
anaphase 1
tetrads separated, opposite poles
Homologous
matching chromosomes (1/2 from mom, 1/2 from dad)
oogenesis
the production of mature egg cells
Nucleic acids are composed of repeated units called nucleotides, each of which is composed of a five-carbon sugar, a nitrogenous base, and a protein.True or False
False
telophas I
nuclear membrane reforms; chromosomes uncoil; after cytokinesis two haploid cells are produced
interphase 1
Chromosomes replicate, cell growth. Meiosis 1 begins with 92 chromosomes
budding
a small axillary or terminal protuberance on a plant, containing rudimentary foliage
prophase II
spindle forms in each daughter cell
life cycle
the generation to generation sequence of stages in the reproductive history of an organism
Interkinesis
no further synthesis of DNA, resting stage
gametes
(eggs and sperm) contain half the complement of chromosomes found in other cells
sexual reproduction
reproduction involving the union of gametes.
polar bodies
do not function as gametes, denature in time, ensure egg has a haploid chromosome number
genome
all the genes of an individual or species. segments of SNA in the sequence of nucleotides in the DNA
fungi, some protists, an algae
gametes fuse to form diploid zygote, meiosis occurs to produce haploid cells
HumaGametes and the Life Cycle of a Sexual Organism
-Our gametes are haploid,
having only one set of
chromosomes
breeding
to produce (offspring); procreate; engender.
heredity
the transmission of genetic characters from parents to offspring: it is dependent upon the segregation and recombination of genes during meiosis and fertilization and results in the genesis of a new individual similar to others of its kind but exhibiting
Random Assortment
Shuffling of homologous chromosomes at Metaphase I -> genetic variety
Sex Chromosomes
23rd pair of chromosomes; determine sex: XX female XY male
Karyotype
Visual display of 23 homologous pairs of chromosomes (one set from each parent)
Locus
A gene's specific LOCATION along a given chromosome
pedigree
an ancestral line; line of descent; lineage; ancestry.
Homologous Chromosomes
Matching pair of chromosomes; one from each parent
genes
the basic physical unit of heredity; a linear sequence of nucleotides along a segment of DNA that provides the coded instructions for synthesis of RNA, which, when translated into protein, leads to the expression of hereditary character.
Gene
Term for a HEREDITARY UNIT at a given location on a chromosome
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