Praxis Middle School Science-The Cell Flashcards
Name the parts of the eukaryotic cell.
- nucleus
- ribosomes
- endoplasmic reticulum
- golgi complex or golgi apparatus.
- lysosomes
- mitochondria
- plastids
- cell wall
- vacuoles
- cytoskeleton
cytoskeleton
composed of protein attached to the plasma membrane and organelles.
What are vacuoles?
Vacuoles hold stored food and pigments. Their size in plants allows them to fill with water in order to provide turgor pressure (without this the plant would wilt)
What is the cell wall?
The cell wall is found in plant cells. It is composed of cellulose and fibers.
- It is thick enough to support and protect.
- It is porous enough to allow water and dissolved substances to enter.
What are plastids?
Plastids are found in photosynthetic organisms.
-They have their own dna and can reproduce as needed for the increased capture of sunlight.
Name three types of plastids.
- chloroplasts: green, function in photosynthesis, capable of trapping sunlight
- chromoplasts: give color to leaves
- amyloplasts: store starch for food
What are mitochondria?
Mitochondria supply energy to the cell
muscles are made of mitochondria because they use a great deal of energy
they have their own dna and are capable of reproducing themselves
What are lysosomes?
Lysosomes contain digestive enzymes
-break down food, waste substances, viruses, damaged cell components and eventually the cell itself
mainly in animal cells
What is the golgi apparatus?
stacked structure
sorts, modifies, and packages molecules that are made in other parts of the cell
these molecules are either sent out of the cell or to other organelles within the cell
What is the nucleus?
The nucleus is the brain of the cell.
Name the parts of the nucleus.
- Chromosomes: dna, rna, and proteins tightly coiled.
- -chromatin: loose structure of chromosomes, called chromatin when the cell is not dividing
- nucleoli: where ribosomes are made, they’re dark spots in the nuclues
- nuclear membrane: contains pores which let rna out of the nucleus
Describe ribosomes.
the site of protein synthesis
What is the endoplastic reticulum?
roadway
allows for transport of materials in and out of the cell
What are the basic unit of living things?
The cell
What are prokaryotic cells?
Prokaryotic cells include only bacteria and blue-green algae
have no defined nucleus
thick cell wall containing amino sugars
What are eukaryotic cells?
Eukaryotic cells are found in protists, fungi, plants, and animals
have cytoplasm, a cytoskeleton, and more complex structures like organelles
What is the purpose of cell division?
To provide growth and repair in body (somatic) cells and to replenish or create sex cells for reproduction
What is mitosis?
the division of somatic (body) cells
two cells result from each division
chromosome number is identical
for cell growth and repair
What are the two parts of mitosis?
- mitotic phase: mitosis and cytokinesis divide the nucleus and cytoplasm, respectively.
- 2. Interphase: the cell grows and copies the chromosomes in preparation for the mitotic phase.
What are the three stages of interphase?
- G1 growth period, when the cell is growing & metabolizing
- S period (synthesis) is where new dna is made
- G2 phase (growth) is where new protein and organelles are being made to prepare for cell division
Cytokinesis
the process whereby the cytoplasm of a single cell is divided to produce two daughter cells
cancer cells do not respond to
density dependent inhibition.
they divide excessively and invade other tissues.
Density dependent inhibition
occurs when the cells crowd one another and consume all the nutrients, thereby halting cell division.
What is cellular respiration?
the metabolic pathway in which food (glucose, etc) is broken down to produce energy in the form of ATP
both plants and animals use respiration to
create energy for metabolism
What is oxidation-reduction (redox reaction)
the process in respiration that releases energy through the sequential loss and gain of electrons
What is the electron transport chain?
the final step in respiration that creates 34 molecules of ATP through oxidative phosphorylation
Photosynthesis
an anabolic process that stores energy in the form of a three-carbon sugar.
photosynthesis’ two stages
- light reactions: solar energy is converted to chemical energy
- calvin cycle: energy from the light reactions is used to reduce carbon to sugar
photosynthesis reverses
electron flow, using the sun’s energy to split water into hydrogen and oxygen and reduce carbon dioxide to glucose.
chloroplast
the site of photosynthesis
autotroph
an organism that makes its own food from the energy of the sun or other elements
What is meiosis?
division of sex cells
four cells or polar bodies result from each division
chromosomes number is half of the two parent cells
recombinations provide genetic diversity
gamete
A gamete is a sex cell or germ cell; sperm and eggs
chromatin
loose chromosomes; the state of chromosomes when the cell is not dividing
chromosome
A chromosome is a tightly coiled, visible chromatin
this state is found when the cell is dividing
What are homologues?
homologues are chromosomes that contain the same information, are of equal length, and contain the same genes
What is a diploid?
2n number, diploid chromosomes are a pair of chromosomes
in somatic cells
haploid
1n number, half a pair (in sex cells)
What are the stages of mitosis?
- interphase: chromatin is loose, chromosomes are replicated, cell metabolism is occurring.
- prophase: chromatin condenses to become visible chromosomes. nucleus disappears. nuclear membrane breaks apart. mitotic spindles form, cytoskeleton breaks down. spindles are pushed to the opposite ends of the cell.
- metaphase: kinetchore fibers attach to the chromosomes, which cause them to line up in the middle of the cell.
- anaphase: centromeres split in half and homologous chromosomes separate. chromosomes are pulled to the poles of the cell, with identical sets at either end.
- telophase: two nuclei are formed, each with a full set of dna identical to the parent cell. nucleoli become visible, and nuclear membrane reassembles. a cell plate is visible in plant cells, and a cleavage furrow is formed in animal cells. the cell is pinched into two cells. cytokinesis or division of the cytoplasm and organelles occurs.
meiosis stages
meiosis 1: chromosomes are replicated; cells remain diploid
prophase 1: replicated chromosomes condense and pair with homologues to form a tetrad. cross over (the exchange of genetic material)
anaphase 1: sister chromatids remain joined and move to the poles of the cell.
telophase 1: two new cells are formed: chromosomes number is still diploid.
meiosis 2: reduces the chromosome number in half
prophase 2: chromosomes condense.
metaphase 2: spindle fibers form again, sister chromatids line up in the center of the cell, centrometers divide, sister chromatids separate
anaphase 2: separated chromosomes move to opposite ends
telophase 2: four haploid cells form for each original sperm germ cell. one viable egg cell gets all the genetic info and 3 polar bodies form with no dna. the nuclear membrane reforms and cytokinesis occurs.
