CH 4 ANATOMY

genes and cellular functions

DNA

polymer of nucleotides

sugar- deoxyribose

phosphate group

nitrogenous base (ATCG)

Purines

A and G

double ring

Pyrimidines

C and T and U single ring

Law of complementary base pairing

sequence of one stand governs the other

(ATGC to TACG)

complimentary to each other

Gene

segment of DNA coding for synthesis of a specific protein

Chromatin

fine filamentous of DNA material complexed with proteins

forms complex loops and coils (very long and thick)

Nondiving cells

protein is slender

genes turn off and on as needed

copy all nuclear DNA

Histones

cluster in groups of 8

DNA winds around the cluster of DNA like thread

proteins

Sister chromatids

identical DNA joined at centromere

kinetochores

protein on each side of centromere play a role in cell division

mioitc spindle joins

Ribonucleic acid (RNA)

sugar- ribose

bases A,U,G,C

single chain

mainly functions in cytoplasm

Messenger RNA (mRNA)

carry dna message exactly identical just replace T with U

Ribosomal RNA (rRNA)

constituent of a ribosome; assist with protein synthesis

Transfer RNA (tRNA)

Short chain transfer amino acids to ribosome

genome

all DNA in one 23-chromosome set

genomics

study of whole genome

genomic medicine

application of knowledge of genome to prediction, diagnose and treatment

genetic code

system enables 4 nucleotides to code for amino acid sequence

base triplet

sequence of 3 DNA nucleotide strands for one amino acid

codon

3 base sequence in mRNA

start codon is aug for methionine

Transcription

FIRST

copying of genetic instructions from DNA to mRNA

utilizes RNA polymerase

Opens DNA helix, puts on proper nitrogenous bases (A+U)

terminator

stop sequence at the end of gene

pre-mRNA

immature from transcription

alternative splicing

variations exons spliced allow for variety of proteins to be produced

one gene can code for more than 1 protein

Translation

SECOND

nucleotide language converted into amino acid language (cytoplasm or Rough ER

translation mRNA

carries code from nucleus to cytoplasm has codons

translation tRNA

delivers single amino acid to ribosome (has anticodon)

translation rRNA

builds peptide chains

large subunit and small subunit

initiation

AUG codon reached, protein synthesis begins

tRNA brings first amino acid

elongation

tRNA binds to A site

creates peptide bond between 1st and 2nd amino acids

peptide grows

termination

ribosome reaches stop codon

ribosome disassembles and dissociates mRNA

polyribosomes

multiple ribosomes

chaperone proteins

guide the folding of newly synthesized proteins

help damaged proteins fold back into functional shapes

post transitional modification

protein assmebled on ER surface, gets modified, remove some amino acid sequence

semiconservative replication

each DNA molecule contains old (parental) DNA and newly synthesized DNA

DNA damage response (DDR)

place to correct replication errors

mutations

change in DNA structure due to replication or environmental factors

G1

INTERPHASE

first gap phase

interval between cell division and DNA replication

synthesizes proteins

S: synthesis phase

INTERPHASE

cell replicates all nuclear DNA and duplicates centrioles

G2

INTERPHASE

second gap phase

interval between DNA replication and cell division

cell repairs DNA replication errors

Mitotic phase

cell replicates nucleus and forms 2 daughter cells

G0 phase

for cells that don’t divide (neutrons or cardiac cells)

functions of mitosis

growth of all tissues and organs after birth

replacement of cells that die

repair damaged tissues

Prophase

package sister chromatids

nuclear envelope disintegrates

metaphase

chromosomes aligned at equator

spindle fibers form mitotic spindle

sister chromatids align

Anaphase

enzyme leaves 2 sister chromatids apart at centromere

sister chromatids separate

telophase

chromosomes cluster to each side of the cell

form daughter nuclei

new nuclear envelope

mitotic spindle disintegrates

cleavage furrow

indentation of cell surface

cytokinesis

division of cytoplasm into 2 cells

cell pinches into 2

cells can divide when..

enough cytoplasm

replicated DNA

supply of nutrients

growth factors

neighboring cells die, open up space

cells can’t divide when…

snug contact with other cells

contact inhibition

M phase

mitosis

3rd phase

metaphase to anaphase determines if cell can proceed to anaphase

cancer

uncontrollable cell division

malignant

cancerous tumors

grow rapidly

tend to metastasize

may stimulate tumor angiogensis

Angiogenesis

growth of blood vessels by energy- hungry tumors

benign

non-cancerous tumors

carcinoma

cancer in epithelial tissue

melanoma

cancer in the pigments of cells in epidermis

carcinogens

environmental cancer causing agents

radiation- uv tanning bed radiation

chemical- cigarette, food preservatives

viruses- papillomavirus, hepatitis c, type 2 herpes

oncogenes

cell division accelerates out of control

receptors stimulate mitosis

tumor- supressor (TS) genes

block development of cancer BUT can be mutated

hereditary

transmission of genetic characteristics from parent to offspring

karyotype

whole chart from large to small (size)

46 chromosomes

23 pairs

homologous chromosomes

22 pairs of autosomes

1 pair of sex chromosmes

diploid (2n)

describes cell with 23 pairs

somatic cells are diploid (body)

haploid (n)

half as many chromosomes as somatic

23 UNPAIRED chromosomes

Germ cells

sex cells (haploid)

female, xx

male xy (y is super small)