Chapter 3 Flashcards
Cell
Is the smallest living subunits of an organism
Human cells vary in size, shape and function
Human cells function interdependently to maintain homeostasis
Major parts of the cell
The cell membrane
A nucleus
Cytoplasm
cell organelles
Which cell has no nucleus?
Red blood cells
Cell membrane
Outer boundary of a cell
made up of phospholipids, cholesterol and proteins
selectively permeable boundary
Role of Phospholipids in Cell membrane
permit lipid-soluble materials to easily enter or leave the cell by diffusion through the cell membrane
Role of Cholesterol in membrane
provides more stabily
Role of proteins in cell membrane
forms pores, carrier enzymes, self antigens and receptors sites for hormones
Cell Nucleus
The control center
Made of DNA,RNA, and protein
Contains Chromosomes -23 pairs
Cytoplasm
Watery Solution that is found between the cell membrane and nucleus and contains organelles
The endoplasmic reticulum (ER)
Transport materials within the cell
Make lips
Rough ER has numerous ribosomes
Smooth ER has no ribosomes
Ribosomes
Makes proteins
Nucleolus
forms ribosomal RNA
Proteasomes
degrade damaged proteins
Golgi apparatus
series of flat membranous sacs
makes carbohydrates
Package materials for secretion from cell
Mitochondria
double membrane, inner membrane has folds called cristae
energy production of cell
contains own genes (37 of em)
Lysosomes
single membrane structure
Digest foreign material in the cell
cleans things
works as the digestive system of the cell
Centrioles
two rod shaped structures perpendicular to one another
organize spindle fibers during cell division
Cilia
sweeps materials across the cell surface
Flagellum
long appendage that enables the cell to move
sperm cells only human cell to have flagellum
Microvilli
folds of the cell membrane that increases a cells surface area for absorption
Cytoskeleton
gives support and shape to the cell
Cellular transport Mechanisms
processes by which cells take in or secrete or excrete materials through the cell membrane
Diffusion
Movement of molecules from an area of greater concentration to an area of lesser concentration
Ex: exchange of gases in the lungs or in body tissues (carbon dioxide,oxygen)
Osmosis
The diffusion of water
water will move from an area with more water to an area with less water
ex:absorption of water by the small intestine or kidneys
Facilitated diffusion
molecules move through a membrane from an area of greater concentration to an area of lesser concentration but they need help (uses carrier enzymes)
active transport
movement of molecules from an area of lesser concentration to an area of greater concentration
ex:absorption of inorganic acids and glucose from food by the cells of the small intenstine
Filtration
Movement of water and dissolved substances from an area of higher pressure to an area of lower pressure (blood pressure)
Ex:formation of tissue fluid in capillaries throughout the body
Phagocytosis
a moving cell engulfs something
Ex:White blood cells engulf bacteria
Pacman of cell
Pinocytosis
A stationary cell engulfs something
Ex:cells of the kidney tubules reabsorb small proteins
think of Venus fly trap
DNA
double strands of nucleotides that is the genetic code in the chromosomes
contains four bases: adenine with thymine (A-T) and guanine with cytosine (G-C)
A gene is the sequence of bases that is the code for one protein
mRNA (Messenger RNA)
Single strand of nucleotide that copy’s DNA gene
contains the triplet code:three bases is the code for one amino acid (a codon)
leaves the DNA in the nucleus, enters the cytoplasm of the cell and becomes attached to ribosomes
tRNA (transfer RNA)
picks up amino acids (from food) in the cytoplasm and transport them to their proper sites(triplets) among the mRNA molecule
has anticodons to match mRNA codons
Ribosomes in protein synthesis
makes proteins
attach to the mRNA molecule
contain rRNA, a ribozyme that forms peptide bonds between amino acids-
cell division
process of which a cell reproduces itself
Stages of mitosis
interphase
prophase
metaphase
anaphase
telophase
cytokines
Mitosis
one cell with diploid number of chromosomes, divides into two identical cells, each with the diploid number of chromosomes
essential for repair of tissues
Interphase
Time between miotic divisions
resting stage where cells aren’t dividing
prophase
1.The chromosomes coil up and become visible as short rods. Each chromosome is really two chromatids (original DNA plus its copy) still attached at a region called the centromere.
2. The nuclear membrane disappears.
3. The centrioles move toward opposite poles of the cell and organize the spindle fibers, which extend across the equator of the cell.
Metaphase
- The pairs of chromatids line up along the equator of the cell. The centromere of each pair is attached to a spindle fiber.
- The centromeres now divide.
Anaphase
Each chromatid is now considered a separate chromosome; there are two complete and separate sets.
2. The spindle fibers contract and pull the chromosomes, with one set pulled toward each pole of the cell.
Telophase
- The sets of chromosomes reach the poles of the cell and become indistinct as their DNA uncoils to form chromatin.
- A nuclear membrane re-forms around each set of chromosomes.
Cytokinesis
- The cytoplasm divides; new cell membrane is formed
Meiosis
more complex process of cell division that results in the formation of gametes, which are egg and sperm cells
Meiosis 1
Dna replication takes place, cell divides into two cells
Meiosis 2
each of these cells has the diploid number of chromosomes and each divides into two cells
dna replication does not take place before meiosis 2
oogenesis
meiosis taking place in the ovaries
spermatogenesis
meiosis takes place in the testes
The egg and sperm cells have ___ number of chromosomes
23
