Chapter 3 part D

cell division (mitotic phase)

cell divides into two

interphase

cell grows & carries on it’s usual activities

What are the two major periods of cell cycle

interphase and mitotic phase

Interphase

During, nuclear material is in uncondensed chromatin state

The brain is always in G what?

G0

replication fork

point where strands separate

replication bubble

active area of replication

Interphase facts

Double stranded DNA helices unwind and unzip (each strand acts as a template for a new complementary strand)

ase means

“I am an enzyme”

M (Mitotic) phase

cell cycle is phase in which division occurs consists of 2 division events mitosis and cytokinesis

Control of cell division

is crucial so cells divide when necessary but do not divide unnecessarily

Mitosis

four stages of mitosis ensure each cell receives a full copy of replicated DNA (prophase, metaphase,anaphase,telophase)

Mitotic Spindle

is an organization of microtubules that are responsible for the movement & organization of chromosomes during cell division

Late prophase

nuclear envelope breaks up

Mitotic spindle does what?

Moves chromosomes around so that there in the equator of the cell in mitosis

Telophase

nucleoli reappear

Cytokinesis

Ring of actin microfilaments contracts to form cleavage furrow

Gene

a segment of DNA that holds the code for one polypeptide

Protein synthesis

DNA is master blueprint that holds the code and directs the order or amino acids in a polypeptide

Protein synthesis code

Consist of 3 sequential bases (triplet code) GGC codes for amino acid proline

What are genes composed of ?

exons and introns

Exons

part of gene that actually codes for amino acids

Introns

noncoding segments interspersed amongst exons

The role of RNA

the go- between molecule that links DNA to proteins, copies the DNA code in nucleus them carries it into cytoplasm to ribosomes

RNA differs from DNA

uracil is substituted for thymine in RNA and RNA has ribose instead of deoxyribose sugar

three types of RNA

messenger RNA (mRNA), Ribosomal RNA (rRNA), transfer RNA (tRNA)

Protein synthesis occurs in two steps

transcription & translation

Transcription

DNA information coded in mRNA

Translation

mRNA decoded to assemble polypeptides

RNA polymerase

the protein that you need to make

Promoter

regions/area of chromosomes

Initiation

RNA polymerase separates DNA strands

Elongation

RNA polymerase string together to the nucleotides

Termination

transcription stops when RNA polymerase reaches special termination signal code

Transcription process involves

mRNA, genetic code, tRNA & ribosomes, translating events, and sometimes the rough ER

Anticodon of tRNA will bind only to condon on what?

mRNA that is complementary

DNA polymerase

attaches to primer & begins adding nucleotides to form new strand.Synthesizes both new strands at one time (one leading & one lagging)

Interphase broken into what ?

three subphases

G1 (growth 1)

vigorous growth & metabolism

G0

cells that permanently cease dividing

S (synthetic)

DNA replication occurs

G2 (gap 2)

preparation for division

leading strand

synthesized continuously

lagging strand

backwards it’s synthesized discontinuously into segment

DNA ligase

an enzyme that splices short segments of discontinuous lagging strand together

early prophase

chromatin condenses forming visible chromosomes, each chromosomes and it’s duplicate are held together by a centromere and its duplicated being synthesizing microtubules that push each centrosome to opposite poles of cells

metaphase

centromeres of chromosomes are precisely aligned at cells equator

metaphase plate

the imaginary plane midway between poles

anaphase

Shortest of all phases, centromeres of chromosomes split simultaneously each sister chromatid now becomes a separate chromosome

checkpoints

key events in the cell cycle where cell division processes are checked & if faulty stopped until repair are made

G1 checkpoint (restriction point)

is the most important of the three major checkpoints. If cell doesn’t pass it enters G0 in which no further division occurs

messenger RNA (mRNA)

single stranded code from DNA template strand is copied with complementary base pairs, resulting in a strand of mRNA (referred to as transcription) mRNA maintains the triplet code (condon) from DNA

ribosomal RNA (rRNA)

structural componet of ribosomes the organelle where protein synthesis occurs along with tRNA helps to translate message from mRNA into polypeptide made in nucleolus

transfer RNA (tRNA)

carrier of amino acid to ribosomes. have a special areas that contain a specific triplet code (anticodon) that allows each tRNA to carry only a specific amino acid

Anticodon of tRNA

will complementary base pair w codon of mRNA at ribosome adding specific amino acids to growing polypeptide chain

transcription factors

looseing histones from DNA in area to be transcribed so DNA segment can be exposed.

Promoter

binding to special sequence of gene to be transcribed (starting point)

trasncription

step of protein synthesis where the language of nuleci acid (base sequence) is trasnlated into the language of protein (amino acid sequence)

genetic code

each three- base sequence on DNA (triplet code) is presented by a complementary three base sequence on mRNA called codon (AUG methylamine start) (UAA, UAG,UGA stop codon)