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41 Cards in this Set

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Chromosomes
The nucleus of eukaryotic cells contains DNA complexed with protein and orginized into a number of linear structures
Homologous
In a diploid organisms, the members of a chromosome pair contain the same genes and that pair at meiosis
Dipoid
Many eukaryotes have two copies of each type of chromosomes in their nuclei, so their so their chromosome complement is said to be diploid 2N
Haploid
The fusion produces a dipoid zygote, which then undergos embryological development. Each gamete has only one set of chromosomes and is said to be haploid (N).
Mitosis
the division of the nucleus
Meosis
egg or cell sperm cells are produced by variation of a cell division called meosis, which yeilds daughter cells that have half as many chromosomes as the parent cell.
What makes homologous chromosomes "homologous"?
each pair is inherited from each parent
What is a gene?
is a strech of nucleotids that encodes a protein
Gene
segment of a DNA molecule that fuctions to encode proteins within the cells. Genes act as paticles might act when they are transferred amoung generations.
asextual reproduction
A single individual is sole parent and passes copies of all its genes on to its offsring.
What type of cell division is associated with asextual reproduction?
By mitotic cell division, in which DNA copied and allocated equally to two daughter cells.
sextual reproduction
usually results in genetic variation; two parents give rise to offspring thathave unique combonations of genes inherited from two parents.
What type of cell division is associated with setual reproduction?
Meosis ise used to make a haploid cell
-known as gametes.
Clone
- a goup of identical individuals
- an individual that reproduces asextually
somatic cells
any cell other than a sperm or ovum.-has 46 chromosomes.
WHat make a homologous chromosomes "homologous"?
The chromosomes that make up a pair-htat havee the same length, centromere posotion, and staining paterns.
-The two chromosomes of ech pair carry gene controlling the same inherited characteristics.
Sex chromosomes
X- female
Y- male
They determine the individuals sex, the X and Y chromosomes.
gametes
Sperm cells and ova are differnet from somatic cells in chromosoms count. Each of the reproductive cells or gametes, has a single set of 22 autosomes plus a single chromosome, either X or Y.
Fertilization or synapsis
By the meaning of sextual intercourse, a haploid sperm cell the fater reaches and fuses with the haploid ovum of the mother.
centrosome
Material present in the cytoplasm of all eukaryotic cells and important during cell division; also called the microtuble organizing center.
spindle microtubles
An assemblage of microtubles that are orchestrates chromosomes movement during eukaryotic cell division
kinetochores
two joined chromatids of a chromosome has kinetochores, a structure of protein and specific sections of chromosomal DNA at the centromere.
synapsis
During prophase of meiosis, the duplicated chromosomes pair with homologies, a process called synapsis
metaphase plate
Microtubles due not attach to teh kinetochores interact with nonkinetochores microtubles from the opposite plate. At metaphase, these microtubles overlap, and the centromeres of all duplicates chromosomes are on a plane midway between the two poles.
- The spindle is noe complete.
chiasmata
-visible in the light microscope are an X-shaped region.
-They represent a crossing of nonsister chromatids, which are two chromatids belonging to seperate but homologous chromosomes.
- chiasmata are the physical manifestation of a genetic rearangment called crossing-over.
Nuclear envelope
MITOSIS
Late prophase the nuclear envelope begings to disapear.
-metaphase has compleatly disappeared.
-telophase- the nuclear envolopes begin forming.
MEOSIS
- Late prophase I begins to disappear.
-telaphase I- nuclear envolopes may form
Nucleolus
MITOSIS:
Early and late prophase Nucleolus begins to disapear.
Telaphase -Nucleolus reforms
cleavage furrow
Cytokinesis occurs by a process known as cleavage. It begins as a shallow groove in the cell surface near teh old metaphase plate. On thr cytoplasmic side of the furrow is a contractile ring of actin microfilaments associated with molecules of the protein myosin.
The contraction of the dividing cells ring of microfilaments is like the pulling of drowstrings. The cleavage firrow deepens until the parent cell is piched in two, producing two compleatly seperated cells.
Cell plates
cytokinesis in plant cells, which have walls, is markedly different. There is no furrow. Instead, during telophase, vesicles derived from the golgi apparatus move along microtubles to the middle of the cell, where they coalesce, produc a cell plate. Cell-wall material carried in the vesicles collect in the cell plate as it grows. The cell plate enlarges until surrounded membrane fuses with the plasma membrane along perimeter of the cell. The two daughte cells results, each with its own plasma membrane. Meanwhile, a new cell wall has formed between them.
independent assortment
A random alignment of homologous chromosomes in metaphase I
-dipoid cell of homologous pairs of chromosomes (one maternal and one paternal).
- 2^n (n=haploid number of the organism)
Cross over
A physical exchange of DNA between homologous chromosomes (prophase I of meosis I).
- produces individual chromosomes that combine gene inherited from our two parents.
- takes place when nonsister chromatids trade places.
Random fertilization
ovum and sperm
Haploid dominant
Its the bulk of the life cycle spent as haploid cell. They go thru sextual reproducion.
-haploid goes thru (mitosis) and get two haploid parents those go thru (meosis) and fuse and form a dipoid. and that diploid goes thru (meosis) and forms new haploid cells and that goes thru mitosis and then that results in haploid adults.
- odd number of pairs.
alternantion of generations
Plants and algae exhibit a thired party type of life cycle.
These types of life cycle include both haploid and diploid.
nondisjunction
The meiotic spindle distributes chromosomes to the daughter cell without error. But there is an occational mishaps known as nondisjunction, in which the members of a pair of homologous chromosomes do not move apart properly during meosis I, or in which sister chromatids fail to seperate during meosis II. In these case, one gamete receives no copy.
aneuploidy
If either of the aberant gametes unites with a normal onee at fertilization, offspring will have abnormal chromosomes.
alternantion of generations
Plants and algae exhibit a thired party type of life cycle.
These types of life cycle include both haploid and diploid.
nondisjunction
The meiotic spindle distributes chromosomes to the daughter cell without error. But there is an occational mishaps known as nondisjunction, in which the members of a pair of homologous chromosomes do not move apart properly during meosis I, or in which sister chromatids fail to seperate during meosis II. In these case, one gamete receives no copy.
independent assortment
A random alignment of homologous chromosomes in metaphase I
-dipoid cell of homologous pairs of chromosomes (one maternal and one paternal).
- 2^n (n=haploid number of the organism)
Cross over
A physical exchange of DNA between homologous chromosomes (prophase I of meosis I).
- produces individual chromosomes that combine gene inherited from our two parents.
- takes place when nonsister chromatids trade places.
Random fertilization
ovum and sperm