أكاديميا - كولنز معاجم الجيب العلمية - البيولوجيا انكليزي - فرنسي - عربي الحرف ١_ m

Academia - Collins Scientific Pocket Dictionaries - Biology
English - French - Arabic Letter 1_ M


medulla
médulle f. moelle f

Marrow. core. The central part of a tissue or organ, such as the kidney in mammals (see cortex).


medulla oblongata (medulla)
bulbe m rachidien

Medulla oblongata (medulla). The back part of the brain in vertebrates is connected to the spinal cord and, in mammals, controls heartbeat, breathing, peristalsis, and other involuntary actions. See brain


meiosis
more f

meiosis. The method of nuclear division occurs when gametes are formed when a diploid nucleus generates four haploid nuclei. This process includes two successive divisions:

First split
Phase 1 The contents of the nucleus become clear

Interstitial development of undifferentiated nucleus contents

It can be seen that each chromosome consists of two chromosomes with a mitotic centromere

Homologous chromosomes form a pair. The cell wall breaks down

Telophase Nuclear membranes form around groups of chromosomes

Anaphase The two mitotic centers repel each other
Between them they carry the chromosomes towards the spindle poles

In the next phase, the nuclear spindle is formed
Or the chromosomes move towards the equator

During the first division of meiosis, homologous chromosomes can exchange genetic material
Their presence side by side, which leads to diversity in the resulting nuclei, and this process is called “crossing over”.

Telophase: Nuclear spindles disintegrate and membranes form around haploid sets of chromosomes

Anaphase: The two centromeres divide and alternate, carrying the chromosomes toward the poles

The second division is a subsequent phase in which two nuclear spindles are formed and the chromosomes move to the equator

The mating of two non-sister chromosomes
Pairing of two sister chromosomes with a centromere
Chromosomal exchange
Chromosomes have not changed

menstrual cycle
Cycle m menstruel

Menstrual cycle (monthly). The reproductive cycle occurs in female primates, monkeys, monkeys, and humans. This cycle is under the control of hormones. The duration of the cycle in female humans is about twenty-eight days, during which the uterus is prepared for implantation. If fertilization does not occur, the new lining of the uterus and the egg are expelled, leading to bleeding from the vagina (menstruation).
fertilization in see
ovulation and humans


meristem
méristème m

Structural tissue. A localized tissue with active cell division responsible for growth in plants. Meristem cells are undifferentiated, but repeated cell division produces new cells that eventually differentiate to form specialized tissues in plants, such as xylem and phloem. . . etc.

Plant hormones control structural tissue activity, and the main structural tissues are the roots, shoots, and cambium.
See cell differentiation
secondary growth and primary growth


metabolic water
Water for metabolism

Metabolic water. A product of aerobic respiration, which constitutes an important source of water for...
Desert animals.


metabolism
metabolism m

Metabolism. The sum of all physical processes

Structural metabolism
Large molecules (such as proteins)
Metabolism
Small molecules (such as amino acids)
Catabolic metabolism

The chemicals that occur within living organisms include the synthesis of compounds (anabolism) and their breakdown (catabolic metabolism). See -bas al metabolic rate.