Cell Structure Flashcards
- Extremely delicate, thin , elastic, living and semi-permeable membrane
- Maintains shape & size of the cell
Protects internal contents of the cell
Plasma Membrane
- Non-living and outermost covering of a cell (def)
- Prevents drying up(desiccation) of cells
- Helps in controlling cell expansion
- Protects cell from external pathogens
cell wall
- Dense spherical body located near the centre of the cell
- Diameter varies from 10-25 µm
- DNA was found
Nucleus
- Nucleus has a double layered covering called
- has pores of diameter
about 80-100 nm
Nuclear Membrane
Chromosomes contain stretches of DNA called
genes
- Jelly-like material formed by 80 % of water
- Present between the plasma membrane and the nucleus
Cytoplasm
- Network of tubular and vesicular structures which are interconnected with one another
- Gives internal support to the cytoplasm
Endoplasmic Reticulum
synthesize secretory proteins and membrane proteins
Rough ER
synthesize lipids for cell membrane
Smooth ER
- Formed by stacks of 5-8 membranous sacs
- Delivers synthesized materials to various targets inside the cell and outside the cell
Golgi body
- Small, spherical, single membrane sac
- Found throughout the cytoplasm
Lysosomes
- Single membrane sac filled with liquid or sap (water, sugar and ions)
- Store various substances including waste products
Vacuoles
Synthesize energy rich compound ATP
Mitochondria
- double membrane-bound organelles found inside plants and some algae.
- storing food
plastids
plastids that produce and store pigments
- gives color found in leaves, fruit…
Chromoplasts
- colourless plastids that store foods.
- storage organs such as fruits, tubers etc
Leucoplasts
- Convert light energy into chemical energy in the form of food
- Double membrane-bound organelles found
mainly in plant cells
- Double membrane-bound organelles found
Chloropasts
- Help in the formation of cilia and flagella
- is the membrane bound organelle present near the nucleus
Centrosome
- Give structural strength to the cell
- Responsible for cellular movements
Cytoskeleton
the process by which a cell nucleus divides to produce two daughter nuclei containing identical set of chromosomes to the parent cell.
Mitosis
is the process by which a cell nucleus divides to produce four daughter nuclei each containing half the number of chromosomes of the original nucleus or cell
Meiosis
It is the division of cytoplasm.
Cytokinesis
It is the period between successive cell divisions consisting of process associated with growth and preparation for mitosis
Interphase
The karyokinesis has got four distinct stages as follows.
- Prophase
- Metaphase
- Anaphase
- Telophase
- Prophase
Formation of spindle fibres is completed and chromosomes are attached to the spindle fibres at the point of centromere
Metaphase
Chromosomes reach the opposite poles and spindle fibres begin to disintegrate
Telophase
This is the shortest phase of the mitotic division
Anaphase
- Progressive condensation and coiling of chromosome fibres.
- Chromosomes are scattered throughout the nucleus in a random manner.
Leptotene
- Chromosomes become shorter and thicker.
Zygotene
Homologous chromosomes lie side by side and this pairing process
Synsapsis
- Exchange of chromosomal segments between non-sister chromatids of the homologous chromosome. This process is called crossing over.
Pachytene
The point of exchange of chromatid during crossing over is called
chiasma.
The homologous chromosomes are attached to each other by
chiasmata
Separation of homologous chromosomes takes place from one another which begins from the centromere to end of the chromosomes
Diplotene
- This stage begins after the complete terminalization of chiasmata
Diakinesis
It is a protein framework, which is found between paired chromosomes. It consists of one central and two lateral elements.
Synaptonemal complex
