Explanation:
During the process of prophase I, the nuclear envelope containing chromosomes has only partly broken down homologous chromosomes are joined together by proteins and a complex or pairing call synapsis- corresponding genes on sister chromatids are aligned precisely.
The syanapsis allows for crossing over which is the exchange of segments of chromosome, between non-sister homologous or similar chromatids crossing over happens at chiasmata, the point where non-sister chromosomes are joined.
Further Explanation:
All the genetic information within the eukaryotic cell is stored within the nucleus as helical DNA. This DNA is tightly wound around histones as chromosomes. In meiosis, the number of chromosomes (2n) is halved to 23 chromosomes (haploid number)through meiotic divisions, producing 4 haploid (n) germ cells or gametes (sperm or eggs), each containing half the number of chromosomes as its parent cell.
In Meiosis I
- homologs pair off into bivalents
- At crossing over: the exchange of segments of chromosome, between non-sister homologous or similar chromatids crossing over happens at chiasmata, the point where non-sister chromosomes are joined in prophase I forming bivalents; tetrads are formed.
- Spindle fibers from centrioles join sister chromatids together at their centromeres in metaphase I, pulling them to the equator of the cell;
- then, in anaphase I, while joined, they are pulled to opposite sides of the cell; the cell body splits and the nuclear envelope reforms in telophase I
In Meiosis II...
- Later, in prophase II, the nuclear envelope disintegrates and mitotic spindle fibers are formed
- independent assortment occurs. in metaphase II of meiosis: spindle fibers attach to centromeres, chromatids align independently at the equator. Genes segregate independently into new combinations as sister chromatids are pulled apart by their centromeres in anaphase II
- in telophase II the cells' nuclei and membrane are then formed with each containing the haploid number (n)
- Following the formation of gametes in the last stage, randomized fertilization occurs in sexual reproduction sperm cells fertilize an ovum to form a zygote. This occurs randomly by chance, to result in a complete set of chromosomes 2n, that is a novel combination of half each parent's number of chromosomes
Learn more about mitosis at brainly.com/question/4303192
Learn more about transcription at brainly.com/question/11339456
Learn more about DNA and RNA at brainly.com/question/2416343?source=aid8411316
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I think it is a sex cell (not sure)
Answer:
a. midbrain
b. thalamus; hypothalamus, epithalamus
c. cerebral aqueduct
d. medulla oblongata
e. choroid plexus
f. pons; medulla oblongata; midbrain
g. hypothalamus
h. cerebrum
i. epithalamus
j. cerebrum
k. cerebellum
Explanation:
The brainstem is the posterior part of the brain that connects the cerebrum with the spinal cord. The brainstem can be divided into three parts: midbrain (i.e., mesencephalon), the pons (i.e., metencephalon), and the medulla oblongata (i.e., myelencephalon). The mesencephalon is a region of the brain composed of the tectum and tegmentum, which play fundamental roles in motor movement, auditory and visual processing. The corpora quadrigemina is found at the tectum region of the midbrain. The diencephalon is a small part of the brain located above the brainstem (between cerebral hemispheres); which contains the thalamus, hypothalamus, subthalamus, and epithalamus. In turn, the epithalamus is composed of the habenular nuclei, pineal gland, and the stria medullaris thalami. The cerebral aqueduct is a narrow channel (approx. 15 mm) in which the cerebrospinal fluid flows between the third ventricle and the fourth ventricle. The medulla oblongata is a long stem-like structure located in the brainstem of the brain, just in the place where the brainstem connects the brain to the spinal cord. The choroid plexus is a complex network of capillaries located at the cerebral ventricles of the brain, which serve to produce cerebrospinal fluid through ependymal cells that line the ventricles of the brain. The cerebellum is a major structure of the hindbrain and consists of the cerebellar cortex and a core of white matter having the cerebellar nuclei.
Answer:
b it describes more on how the rates and how the diversity
of an ecosystem
Explanation:
Answer:
The water cycle consists of three major processes: evaporation, condensation, and precipitation. Evaporation is the process of a liquid's surface changing to a gas. In the water cycle, liquid water (in the ocean, lakes, or rivers) evaporates and becomes water vapor.
Explanation: