DNA Flashcards
a complex molecule containing the genetic information that makes up the chromosomes
-two polynucleotide chains
-hydrogen bonds hold nitrogenous bases together
-forms a helix
DNA
What are the four bases in DNA?
adenine, thymine, cytosine, guanine
How do the four bases in DNA pair together?
A-T; C-G
double ring; adenine, guanine
purines
single ring; cytosine, thymine
pyrimidines
Nitrogenous bases are united by what?
hydrogen bonds
one strand determines the base sequence of another
Law of Complementary Base Pairing
genetic instructions for synthesis of proteins
genes
segment of DNA that codes for a specific protein
gene
all the genes of one person
-humans have an estimated 20,000 to 25,000 genes
-2% of total DNA
genome
delivers genetic information from nucleus to cytoplasm
-single polynucleotide chain
messenger RNA (mRNA)
making of mRNA
-step from DNA to mRNA
-occurs in the nucleus where DNA is located
-copying genetic instructions from DNA to RNA
transcription
a system that enables these four nucleotides to code for the amino acid sequence of all proteins
genetic code
a sequence of three DNA nucleotides that stands for one amino acid
base triplet
3 base sequence on mRNA
codon
step from mRNA to protein
-most occur in cytoplasm
The master sequence for the protein is now coded in the mRNA. Each group of three nucleotide codes for one amino acid, and is therefore called a codon
translation
change in genetic information
-results when: extra bases are added or deleted; bases are changed
mutation
the process of making a copy of DNA
DNA replication
the cell’s life cycle that extends from one division to the next
cell cycle
Phases of the cell cycle:
-interval between cell division and DNA replication
-accumulates materials needed to replicate DNA
G1 phase (first gap phase)
Phases of the cell cycle:
-duplicates centrioles
-DNA replication occurs
S phase (synthesis phase)
Phases of the cell cycle:
-interval between DNA replication and cell division
-finishes centriole duplication
-synthesizes enzymes that control cell division
-repairs DNA replication errors
G2 phase (second gap phase)
Phases of the cell cycle:
-cell replicates its nucleus
-pinches in two to form new daughter cells
M phase (mitotic phase)
transmission of genetic characteristics from parent to offspring
heredity
chart of 46 chromosomes laid out in order by size and other physical features
karyotype
chromosomes that have the same sequence of genes and the same structure
homologous chromosomes
any cell with 23 pairs of chromosomes (somatic cells)
diploid cell
contain half as many chromosomes as somatic cells: sperm and egg cells (germ cells)
haploid cell
the location of a particular gene on a chromosome
locus
different forms of gene at same locus on two homologous chromosomes
alleles
an allele whose trait always shows up in the organism when the allele is present
dominant allele
an allele that is masked when a dominant allele is present
recessive allele
the alleles that an individual possesses for a particular trait (genetic makeup)
genotype
an observable trait; the trait that is actually seen
phenotype
two identical alleles for a trait
homozygous allele
different alleles for that gene
heterozygous allele
trait controlled by two or more genes
polygenic
mutation on chromosome 3 that blocks the breakdown of tyrosine
alkaptonuria
carried on the X and Y chromosomes, and therefore tend to be inherited by one sex more than another
sex-linked traits
slow growth; contain in fibrous capsule; will not metastasize; usually easy to treat
benign tumor
cancer; fast growing; metastasize; give off cells that seed the growth of multiple tumors elsewhere
malignant tumor
medical specialty that deals with both benign and malignant tumors
oncology
in-growth of blood vessels stimulated by energy-hungry tumors
tumor angiogenesis
What are some risk factors for breast cancer?
age, gender, family history, race, estrogen exposure
