Sexual Reproduction And Meiosis Flashcards
No copulation, sperm is spread in a large area, numerous female gametes produced, zygotes develop outside parents; usually occurs in an aquatic environment
External fertilization
Common in fish, amphibians, coral and algae
External fertilization
Three categories of internal fertilization and how offspring are produced
Oviparity, ovoviperity, viviparity
Lay eggs, little to no embryonic development inside the mother but inside an egg; All birds, certain fish, reptiles, and amphibians
Oviparity
Fertilized eggs retained inside parent until hatching; certain sharks, lizards and snakes
Ovoviparity
Embryo develops in female body; mammals, some reptiles, some insects
Viviparity
Asexual reproduction where an egg develops without fertilization
Parthenogenesis
Types of Parthenogenesis- asexual reproduction
Vertebrates: amphibians, lizards, sharks (hammerheads)
Found in birds, Crustaceans, some fish, reptiles and insects
ZW sex determination system (e g. ZW - hen, ZZ - Rooster)
The ZW sex determination system has how many chromosomes?
33 sets
Sex also can be determined by egg incubation temperature, not chromosomes. Common in reptiles like turtles and alligators via….
Environmental sex determination
Mature, haploid reproductive cell (ovum or sperm)
Gamete
Having one of each type of chromosome characteristic of the species, one complete set
Haploid (n)
Having two sets of chromosomes the somatic cells or the cells of the body and humans
Diploid (2n)
Process that begins in immature reproductive cells, called germ cells, in the developing male and female gonads of sexually reproducing eukaryotes
Meiosis
true or false: Germ cells are diploid and have 46 chromosomes (2 sets)
True
True or false: Germ cells are found in the male and female gonads; in the ovarian follicles in human females and semi-niferous tubules of the testes in human males
True
Meiosis will take the 46 chromosome germ cell through two rounds of cell division to create four ….
Haploid gametes (cells)
Haploid gamete cells mature into
Oocytes (eggs) in female and sperm in male
Crossing over occurs in
Prophase 1
Independent assortment occurs
Between metaphase 1 and anaphase 1
Random fusion of gametes occurs
After telophase 2
3 methods of increasing genetic diversity in sexual reproduction
Crossing over, Independent assortment and random fusion of gametes
Considered the reduction round (diploid to haploid)
Meiosis 1
Considered the division round: resembles a mitotic division (sister chromatid separate)
Meiosis 2
Occurs in prophase 1; genetic recombination between non-sister chromatids; allows the homologues to exchange alleles
Crossing Over
Spindle apparatus forms, chromosomes coil together and become visible, nuclear envelopes dissolves, tetrads form and crossing over occurs. Microtubules from opposite poles attached to each homologue (not to each sister chromatid)
Prophase 1 (of Meiosis 1)
Chromosomes align on metaphase plate
Metaphase 1 (meiosis 1)
Microtubules of the spindle shorten, homologous (x-shaped) separate from each other and move to opposite poles, sister chromatids remain attached to each other at their centromeres
Anaphase 1 (meiosis 1)
Nuclear envelopes reform
Telophase I (meiosis 1)
Chromosomes condense, nuclear envelopes dissolve and a new spindle apparatus forms
Prophase 2 (meiosis 2)
Chromosomes align at metaphase plate
Metaphase 2 (meiosis 2)
Sister chromatid s separate
Anaphase 2 (meiosis 2)
Nuclear envelope reforms, chromosomes relax, cytokinesis follows to create four haploid cells that will mature into gametes
Telophase II (meiosis 2)
True or false: a centromere is a region
True
True or false: a kinetochore is a protein
True
To identical copies of a chromosome that are joined together at the centromere,
formed during DNA replication, and separate during cell division to ensure each new daughter cell receives a complete set of chromosomes
Sister chromatids
To identical copies of a chromosome that are joined together at the centromere,
formed during DNA replication, and separate during cell division to ensure each new daughter cell receives a complete set of chromosomes
Sister chromatids
pairs of chromosomes in a cell that are identical in structure and gene content, with one chromosome from each pair inherited from the organism’s mother and the other from the father
Homologues
a genetic principle stating that alleles of different genes segregate into gametes (sperm and egg cells) independently of one another
Independent assortment
True or false: germ cells are diploid (2 eggs)
True
Germ cells go through DNA replication in what phase
S
True or false: diploid number is restored at fertilization
True
Fusion of a sperm nucleus and an egg nucleus, resulting in a single celled zygote
Fertilization
Diploid (2n) sell formed by fusion of gametes; first cell of a new individual, with two sets of chromosomes, one from each parent
Zygote
True or false: meiosis requires two rounds of division to create four haploid cells
True
True or false: mitosis goes through one round of cellular division and creates two identical daughter cells
True
True or False: There is a much greater genetic variation with four resulting haploid cells in meiosis than we do in mitosis with producing two identical daughter cells
True
True or false: mitosis occurs in a body cells/somatic cells
True
True or false: meiosis occurs in sex cells (gametes)
True
Homologous chromosomes separate in? (Haploid to diploid/46 to 23 chromosomes)
Meiosis 1
Sister chromatids are separated in?
Meiosis 2 (division round)
Occurs one in 20,000 births, brain and heart defects, severe mental retardation, seizures, extra fingers or toes, whole split or cleft in the iris, close set eyes or eyes may fuse together, death may occur in 2 to 5 days
Pateau syndrome (trisomy 13)
Chromosome number can change permanently, usually resulting from________ from which arises_______.
Non-disjunction, aneuploidy
Failure of chromosomes to separate during cellular division
Non-disjunction
Cell with too many or too few copies of a particular chromosome (trisomy, monosomy)
Aneuploidy
True or false: trisomy =3, monosomy = 1
True
1 in 3000 births, brain abnormalities, heart defects, kidney, mouth formation, cleft lip and palette, rocker bottom feet, exomphalos (intestines held in sac outside abdomen), life expectancy 5 to 15 days
Edwards syndrome (trisomy 18)
1 in 900 births, almond-shaped upward slanting eyes, short body parts, loose joints, moderate to severe mental impairment, life expectancy up through adulthood
Down syndrome (trisomy 21)
True or false: The rate of down syndrome increase with age of mother
True
The only non-fatal monosomy, short stature, broadchest, webbed neck, life expectancy into adulthood
Turner’s syndrome (monosomy X or XO)
Tall stature, wide hips, poor muscle tone, reduced male sex characteristics, male breast development, small testicular size
Kleinfelter’s syndrome (XXY)
True or false: other andeuploidy karyotypes are generally not found because they do not occur or they are too severe to survive development, most end in abortions (20 to 50%)
True
What is a non-sex chromosome?
Autosome
The exchange of genetic material between homologous chromosomes resulting in chromosomes that incorporate genes from both parents of the organism forming reproductive cells
Crossing over
A visual representation of a cross between two individuals in which the gametes of each individual are denoted along the top and side of a grid, respectively, and possible zygote genotypes are recombined at each box on the grid
Punnett square
Describes a trait that masks the expression of another trait when both versions of the gene are present in an individual
Dominant
In a heterozygote, expression of two contrasting alleles such that the individual displays an intermediate phenotype
Incomplete dominance
