The Cells, Tissues, and Organization of the Body Flashcards
zygote
results from the fusion of the ovum (female egg cell) and the spermatozoon (male sex cell)
from it the human body develops
cell consists of
plasma membrane inside which are a number of organelles
(small working parts/small organs) suspended in a watery fluid called cytoplasm
What are Organelles
have individual and highly specialized function, and are often enclosed in their own membrane within the cytoplasm
Types of Organelles
include the nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, and the cytoskeleton
plasma membrane
consists of two layers of phospholipids (fatty substances) with protein and sugar molecules embedded in them & lipid cholesterol
The membrane proteins perform several vital functions:
- Branched carbohydrate molecules attached to the outside of some membrane protein molecules give the cell its immunological identity
- They can act as specific receptors (recognition sites) for hormones and other chemical messengers
- Some are enzymes
- Some are involved in transport across the membrane
nucleus
largest organelle and is contained within the nuclear envelope, a type of membrane similar to the plasma membrane but with tiny pores through
which substances can pass through
contains the body’s genetic material, which directs all the metabolic activities of the cell.
46 chromosomes, which are made from deoxyribonucleic acid (DNA).
nucleolus
involved in manufacturing (synthesis) and assembly of the components of ribosomes
Mitochondria
membranous, sausage-shaped structures in the cytoplasm of the cell, sometimes described as the “power house” of the cell
involved in aerobic respiration, the processes by which chemical energy is made available in the
cell
Ribosomes
e tiny granules composed of RNA and proteins.
create proteins from amino acids using RNA as the template.
- including the enzymes required for metabolism
endoplasmic reticulum (ER)
s an extensive series of interconnecting membranous canals in the cytoplasm of the cell.
types of endoplasmic reticulum (ER)
smooth and rough
smooth ER
synthesizes lipids and steroid
hormones, and is also associated with the detoxification of some drugs.
rough ER
studded with ribosomes which are the site of synthesis of proteins, some of which are exported from the cell.
Golgi apparatus
consists of stacks of closely folded flattened membranous sacs
present in all cells but is larger in those that synthesize and export proteins
Lysosomes
one type of secretory vesicle with membranous walls, which are
formed by the Golgi apparatus.
contain a variety of enzymes involved in breaking down fragments of organelles and large molecules inside the cell into smaller particles that are either recycled, or extruded from the cell as waste material.
cytoskeleton
consists of an extensive network of tiny protein fibers.
These fibers are microfilaments,
microtubules, centrosomes
, cell extensions
microfilaments
the smallest fibers which provide structural support
microtubules
large contractile protein fibers that are involved in the movement of organelles within the cell, chromosomes, and cell extensions
centrosomes
directs organization of microtubules within the cell
cell extensions
project from the plasma membrane in some types of cells, allowing for movement of the cell
mitosis
a process that results in two new genetically identical daughter
cells
gametes
sex cells
cell cycle
period between two cell divisions
has two phases, these being interphase and mitosis
Interphase
considered the longer of the two phases
divided into three separate stages:
* First gap phase - the cell grows in size and volume.
- Synthesis of DNA - the chromosomes replicate forming two identical copies
of DNA. - Second gap phase - there is further growth and preparation for cell division.
Mitosis phases
continuous process which involves four distinct phases, these are:
- Prophase - chromatin replicates and becomes tightly coiled
- Metaphase - chromatids align on the centre of the mitotic spindle, attached at
their centromeres - Anaphase - the centromeres separate, and one of each pair of sister chromatids
migrates to each end of the spindle - Telophase - the mitotic spindle disappears, the chromosomes uncoil and a
nuclear envelope reforms
Prophase
chromatin replicates and becomes tightly coiled
Metaphase
chromatids align on the centre of the mitotic spindle, attached at
their centromeres
Anaphase
the centromeres separate, and one of each pair of sister chromatids
migrates to each end of the spindle
Telophase
the mitotic spindle disappears, the chromosomes uncoil and a
nuclear envelope reforms
active transport
transport of substances up their concentration gradient (uphill), or rather, from a lower to a higher concentration.
chemical energy in the form of ATP drives specialized protein carrier molecules that transport substances across the membrane in either direction.
The carrier sites are specific and can be used by only one substance, therefore the rate at which a substance is transferred depends on the number of sites available.