Full Chapter 12 Flashcards
Condensed chromatin structure formed when cells replicate.
Chromosomes
One half of a chromosome. Two sister chromatids are joined by a centromere to form a chromosome.
Chromatid
One of two chromosomes that are genetically identical and held together at the centromere.
Sister chromatids
One of the different forms of the same gene
Alleles
Governs expression of a trait
Gene
X or Y chromosome; determines genetic sex (Female = XX; Male = XY)
Sex chromosomes
Chromosomes with the same gene sequence
Homologous chromosomes
Cells with two pairs of homologous chromosomes. The ——— number in humans is 46, or 23 pairs.
Diploid cell
Cell with half the number of chromosomes as diploid. Human gametes, or reproductive cells (egg and sperm cells), are ———. (The ——— number of chromosomes in a species is designated as n. In humans, n = 23, and a diploid cell has 2n chromosomes (2n = 46).)
Haploid cell
An individuals complete set of chromosomes.
Karyotype
The cell grows quickly during this phase, making new cell molecules (except DNA).
G1 phase
The DNA in the chromatin replicates to create an identical copy of DNA. These two identical chromosomes, called sister chromatids are joined at the centromere.
S phase
This second growth stage lets the cell rebuild its reserves of energy to prepare for division. As well, the cell manufactures proteins and other molecules to make structures required for division of the nucleus and cell.
G2 phase
Refers to a body cell
Somatic cell
Sex cell (egg or sperm)
Germ cell
Growth phase; includes G1, S phase, and G2
Interphase
It is a continuous process that involves two stages: mitosis and cytokinesis
Division Stage
Division of the cell’s nucleus where the daughter cells receive the exact number of chromosomes and genetic makeup as the parent cell.
Mitosis
Separation of the cytoplasm and the formation of two new daughter cells; occurs after telophase of mitosis
Cytokinesis
Chromosome other than sex chromosome
Autosome
A membrane that encloses the nucleus
Nuclear membrane
Is a barrel-shaped cell structure involved in the organization of the mitotic spindle and in the completion of cytokinesis
Centrioles
One of a network of fibres that forms the spindle apparatus during cell division (mitosis); made of mictotubules, hollow tubes of protein that facilitate movement of chromosomes within a cell.
Spindle fibres
Is a region of DNA typically found near the middle of a chromosome where two identical sister chromatids come closest in contact.
Centromere
A plasma membrane invagination at the cell division site.
Cleavage furrow
A eukaryotic cell formed by a fertilization event between two gametes. (Sexual reproduction requires the fusion of a male and a female reproductive cell to produce a ——.
A —— receives half its genetic material from the female parent and the other half from a male parent.
Zygote
- a advanced cell
- a more complex cell with a true nucleus and membrane bound organelles such as E.R., ribosomes, Golgi apparatus, etc…
- ex. These are in cineplex organisms such as humans and other animals. (Ex: blood cells, liver cells, muscle cells, nerve cells)
Eukaryotic
- primitive cell
- a simple cell with NO true nucleus
- ex: simple organisms have these cells. (Bacteria, amoeba, paramecium, single cell organisms)
Prokaryotic
The life of a cell. Can be divided into two main stages: interphase and cell division.
Cell cycle
The long strands that form chromosomes and contain DNA, RNA and various proteins. Found in the nucleus of cells.
Chromatin
- The chromatin condenses into tightly packed chromosomes.
- The nuclear membrane breaks down, releasing the chromosomes into he cytoplasm.
- The nucleolus disappears.
- One pair of centrioles move apart to opposite poles of the cell.
As the centrioles move apart, a network of fibres called the spindle fibres forms between them. Each spindle fibre is made of microtubules.
Prophase
- The spindle fibres guide the chromosomes to the equator, or centre line, of the cell.
- The spindle fibres from opposite poles attach to the centromere of each chromosome.
Metaphase
- Each centromere splits apart and the sister chromatids separate from one another.
- The spindle fibres that link the centromeres to the poles of the cell shorten. As there fibres shorten, sister chromatids are pulled to opposite poles.
- At the end of anaphase, one complete diploid set of chromosomes has been gathered at each pole of the elongated cell.
Anaphase
- The chromatids begins to unwind into longer and less visible strands of chromatin.
- The spindle fibres break down.
- A nuclear membrane forms around each new set of chromosomes.
- A nucleolus forms within each new nucleus.
Telophase
male or female reproductive cell
Gamete
A four-part structure that forms during prophase I of meiosis and consists of two homologous chromosomes, each composed of two identical chromatids.
It’s made up of a pair of sister chromatids synapsed with another pair of sister
chromatids. In the middle of it, two homologous but non-identical chromatids, which are called non-sister chromatids, lie side by side. This alignment of non-sister chromatids plays an important role in genetic recombination.
Tetrad
a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. This process is required to produce egg and sperm cells for sexual reproduction.
Meiosis
- In prophase I, each pair of homologous chromosomes align side by side. This aligning of homologous chromosomes is called…
- The pairing of two chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. It takes place during prophase I of meiosis.
synapsis
- While they are lined up side by side, non-sister chromatids may exchange pieces of
chromosome in a process known as… - The exchange of genes between two chromosomes, resulting in non-identical chromatids that comprise the genetic material of gametes. This process occurs during Prophase I of Meiosis, just prior to chromosome alignment and splitting of the cell.
Crossing Over
- two homologous but non-identical chromatids
- contain the same genes but may have different alleles at the same loci. They are not exact copies of each other.
non-sister chromatids
male gamete
Sperm Cell
female gamete
Ovum (egg)
process of male gamete production
Spermatogenesis
process of female gamete production
Oogenesis
involves the production of gametes by meiosis, followed by fertilization
between genetically distinct parental gametes to produce genetically distinct offspring.
Sexual reproduction
the reproductive process in which a parent organism produces genetically identical offspring.
Asexual reproduction
a diploid germ cell (spermatogenesis)
spermatogonium
a diploid germ cell (genesis)
oogonium
a type of asexual reproduction typically observed in prokaryotes (bacteria) and a few single-celled eukaryotes. In this method of asexual reproduction, there is a separation of the parent cell into two new daughter cells.
binary fission
involves the transfer of genetic material from one cell to another by cell-to-cell contact through a bridging structure called a pilus. This creates cells with new genetic combinations, and thereby provides a chance that some cells may be better adapted to changing conditions.
conjugation
is a form of asexual reproduction in which a complete but miniature version of the parent grows out from the parent’s body. The new organism then separates to become an independent organism. An example can be found in Hydra.
budding
growth of a new plant from a modified stem. For example, strawberry plants can spread across a garden by extending thin creeping stems. A new
strawberry plant develops at the end of each stem.
Vegetative reproduction
a new organism forms from a part of a parent. In the cultivation of potatoes, for example, entire new plants are grown from a fragment, or tuber, of a parent plant. Some animals, such as sea stars, can reproduce by fragmentation.
Fragmentation
a form of asexual reproduction in which an unfertilized egg develops into an adult. In honeybees, for example, the queen bee lays both fertilized and unfertilized eggs. The fertilized eggs develop into female worker bees, while the unfertilized eggs develop into male drones. The whiptail lizard is another animal that reproduces by parthenogenesis.
Parthenogenesis
Several different species have evolved a mechanism to reproduce asexually and disperse their offspring long distances. A —— is a structure that contains genetic material and cytoplasm surrounded by a protective sheath or wall. The wall protects the contents until conditions are favourable, at which point the spore wall opens and the organism begins to develop. Because spores tend to be very small, they are readily dispersed in water and by the wind. (Bread mold, mushrooms, etc.)
spore
The male reproductive structure of a flower. Made up of the Anther and Filament.
Stamen
The female reproductive structure of a flower. Made up of the Stigma, Style and Ovary.
Pistil
occurs when the pollen (male gametophyte) lands on the female reproductive structure of a plant of the same species.
Pollination
A flower possessing BOTH male and female reproductive structures. This type of flower is capable of undergoing self – pollination (fertilization).
Perfect Flower
A flower possessing EITHER male or female reproductive structures only.
In general, flowers have four organs: sepals, petals, stamens, and one or more pistils.
Imperfect Flower
Sticky portion on top of the style in a flower.
Function: Trap pollen from the air for reproduction.
Stigma
Long slender tube leading from the stigma to the ovary in a flower.
Function: Passage way for pollen leading to the ovary.
Style
Reproductive structure of a flower that contains eggs. Eggs are created by meiosis in this structure. Eggs contain the haploid (n) chromosome number. Function: Site of fertilization within a flower.
Ovary
Reproductive structure of a flower that contains pollen. Pollen is created by meiosis.
Function: Create pollen for fertilization.
Anther
Small round structure located within the anther of a flower that contains the male sex cells (sperm). It contains haploid (n) the chromosome number as the parent cell.
Pollen
Long slender stalk that holds up the anther.
Filament
an outgrowth of the ovary of a seed plant that after fertilization develops into a seed (a small egg.)
Ovule
the vegetative nucleus that guides the growth of the pollen tube when it enters the pistil. The main function is to control and direct the growth of the pollen tube.
tube nucleus
a hollow tube-like structure formed from pollen deposited on the stigma. It belongs to the male reproductive structure. It is not a nutrient-rich structure. (a unique and specialized structure in plants. Its sole purpose is to deliver sperm cells to the female gametophyte for double fertilization. Essentially, it is a thread–like structure spanning from the pollen shell toward the tip.)
Pollen tube
