Chapter 6: Overview of Cell biology

Cell membrane

the frail, semipermeable, flexible structure encasing and surrounding the human cell that functions as a barrier to protect cellular contents from the outside environment and also controls the passage of water and other materials into and out of the cell

Cytoplasm

the protoplasm that exists outside the cell nucleus and is primarily composed of water, but also contains proteins, carbohydrates, lipids, salts, minerals

What is the cell membrane made of?

lipids and proteins

Nucleus

contains the genetic or hereditary, material, DNA, and proteins. Also contains the nucleolus. the nucleus controls cell division and multiplication and the biochemical reactions that occur within the cell, also directs protein synthesis

Chromosome

tiny rod shaped bodies that under a microscope appear to be long threadlike structures that become visible only in dividing cells

Chromosomes are composed of what?

protein, the genetic material DNA

In a normal human body how many different chromosomes are there and how many pairs?

46 chromosomes and 23 pairs in each somatic cell

Chromatid

one of the two identical halves of a copied chromosome

Centromere

specialized, constricted central region of a chromed that holds duplicate sister chromatids together and acts as an attachment site for cell division fibers

Centrosomes

located in the center of the cell near the nucleus. they contain centrioles

Process of centrosome structure?

during cell division, two centrioles combine together with some other special proteins and then form the structure, comprised of microtubles

Mitochondria

the large double membranous oval or bean shaped structure functions as the powerhouse of the cell because they supply energy for all cellular function

What are nucleic acids?

dna and rna

DNA

composed of two long sugar phosphate chain, which twist around each other in a double helix configuration and are liked by pairs of nitrogenous organic bases

Adenine and guanine are what?

purines

Cytosine and thymine are classified as what?

pyrimidines

RNA

long single stranded chain of cells that processes protein

What is the process of mitosis?

when somatic cells divide they undergo a process in which the nucleus divided, followed by the division of the cytoplasm

Meiosis

genetic cells undergo a process of reduction division

What happens when mitosis occurs?

a parent cell divides to form 2 daughter cells identical to the parent cell

What is interphase composed of?

G1, S, G2

What does G1 do?

is the earliest period and the gap in the growth of the cell that occurs between mitosis and DNA synthesis,

What happens during G1?

a form of RNA is manufactured in the cells that are to reproduce. this RNA is needed before actual DNA creation can effectively begin

What is the S phase?

each DNA molecule contained within the chromosome is first copied and then is divided into two individual sister components called chromatids, each containing DNA molecule. by the end of this phase these chromtids will join together to form a new chromosome that has an X shaped structure

What’s the definition of centromere?

two chromatids join together

What happens in G2 phase?

cells manufacture certain proteins and RNA molecules, which are needed for initiating and completing the subsequent mitosis process

What happens in prophase?

the nucleus enlarges, the DNA complex coils up tightly and the chromatids become visible, next the nuclear membrane disappears and the centrioles migrate to opposite sides of the cell and begin to regulate the formation of the mitotic spindle, the delicate fibers that are attached to the centrioles and extend from one side to the other across the equator of the cell

What happens in Metaphase?

the mitotic spindle forms between the centrioles. each chromosome lines up in the center or equator, during this process cell division can be stopped and visible chromosomes can be visible

What happens in Anaphase?

begins with the breakdown of proteins called securing and then the sister chromatids separate. the spindle fibers pull each d apart and move them to opposite ends of the cell, this ensures that new cell will receive an identical set of chromosomes

What happens during Telophase?

the chromatids undergo changes in appearance by uncoiling and becoming long loosely spiraled threads. a new nuclear membrane forms around each set of chromosome, creating two new nuclei

Meiosis

is a special type of cell division that reduces the number of chromosomes in each daughter cell, to half the number of chromosomes in the parent cell