UNIT 1 - Final Review Flashcards
Chromatid
condensed chromosomes
Chromatin
uncondensed chromosomes
Senescence
the process of aging
Totipotent
describes a nucleus that is able to bring a cell from egg to adult
Metastasis
Cancer cells can dislodge from a tumour and move to another area
Cancer cells
cannot carry out normal functions of cells. Are almost always in mitosis.
Benign vs. malignant tumours
benign = remains at site, does not cause serious problems
malignant = may metastasize and impair functions of organs
Telomeres
Caps at the ends of chromosomes.
Reduce in length each time a cell goes through the cell cycle and divides
Telomerase
allows cancer cells to maintain telomere length
homologous chromosomes
paired chromosomes; similar in shape size and gene arrangement; are not identical
meiosis aka…
reduction division
tetrad
(meiosis) 4 chromatids
synapsis
the pairing of homologous chromosomes
Kinetochore
region of centromere that links sister chromatids to spindle
segregation
the partitioning of genetic material into two daughter cells (meiosis/reduction division)
Plant life cycle: Alternation of Generations
alternation between haploid and diploid vice versa
syndrome
a group of disorders that occur together.
down syndrome
trisomy 21. Mentally challenged, short, full face, large tongue, large forehead
Turner’s syndrome
monosomic disorder. Female that has a single x chromosome.
klinefelter’s syndrome
The child inherits the XX chromosome and Y chromosome. Appears male at birth; during puberty high levels of female sex hormones are produced
Teratogens
chemicals that cause abnormalities in embryos
Amniocentesis
an ultrasound is used to locate the position of the fetus within the mother’s womb.
A syringe draws amniotic fluid, which is spun in a centrifuge, cultured, then karyotyped.
Chorionic villi sampling (CVS)
cells are drawn from the chorionic villi (placenta). More invasive, but can be performed earlier in pregnancy.
nucleotide
phosphate, sugar, N-base
Chromosomes are made of….
DNA
DNA is made of….n
nucleotides
Segments of DNA are…
genes
DNA nitrogen bases:
Adenine, thymine, cytosine, guanine
Chagraff’s rules
amount of A=T, C=G
Rosalind Franklin
collected x-ray data on DNA
James Watson and Francis Crick
proposed a 3-D model of DNA using Franklin’s data (double helix/twisted ladder)
Backbone of (DNA) ladder
deoxyribose sugar and phosphate
What forms the rung of a DNA ladder
Nitrogen bases (ACTG). N-bases are connected by hydrogen (weak) bonds.
anti-parallel
(2) DNA strands are parallel, but run in opposite directions.
Purine + pyrimidine
these always pair together.
DNA replication is…s
semi-conservative
DNA helicase
breaks the H-bonds between complementary base pairs.
Replication fork
The point where the two strands of DNA separate
DNA polymerase III
links free nucleotides that have bases complementary to the template strand.
DNA polymerase I
proofreader that cuts out RNA primers and replaces them with the appropriate DNA nucleotide
Leading strand
strand that is made continuously during DNA replication
lagging strand
synthesized in short fragments during DNA replication
DNA ligase
glues the sugar-phosphate backbone and DNA fragments together
RNA sugar name…
ribose sugar
RNA does not contain…., instead it contains….
thymine; uracil
RNA is ____ stranded
single
DNA is located in ____, proteins are made in ____
nucleus, cytoplasm
messenger RNA (mRNA)
reads the DNA code and exits through nuclear pores, and carries the message to the ribosomes
Transcription process (3 steps)
Initiation, elongation, termination
Initiation (transcription)
RNA polymerase binds to DNA
Elongation (transcription)
DNA unzips. nucleotides from mRNA find appropriate pairs using single strand of DNA as a blueprint
Termination (transcription)
single stranded RNA exits through nuclear membrane. DNA rezips.
Codons
blocks of 3 nucleotides decoded into the sequence of amino acids
Translation (3 steps)
Initiation, elongation, termination
Initiation (translation)
mRNA attaches itself to the ribosome. The initiator codon turns on protein synthesis
Elongation (translation)
transfer RNA (tRNA) picks up amino acids around cytoplasm and shuttles it to mRNA. ribosomal RNA (rRNA) fuses the amino acids into a long chain.
tRNA
contains an anticodon that complements the codon of the mRNA. (it picks up the protein the mRNA codes for).
Termination (translation)
terminator codon turns synthesis off
Recombinant DNA
fragment of DNA composed of sequences from at least 2 different sources.
Genetic Transformation
introduction and expression of foreign DNA in a living organism
Restriction enzymes
molecular scissors that cut double-stranded DNA at a specific base pair sequence → recognition sites
Restriction endonucleases
molecular scissors that cut double-stranded DNA at a specific base pair sequence → recognition sites
DNA ligase
helps to restore fragmented chromosomes when damaged. Creates recombinant DNA by joining pieces of DNA from different sources together
Taq polymerase
enzyme used in polymerase chain reaction
polymerase chain reaction (PCR)
- The mixture is heated, breaking the H-bonds in DNA. DNA is separated into single-stranded DNA templates.
- Mixture cools, primers form H bonds with DNA template
- Taq polymerase forms new DNA strand from DNA template using complementary base pairings
- Cycle of heating and cooling is repeated
Gel electrophoresis
Method used to separate mixtures of DNA, RNA or proteins according to molecule size.
Molecules are pushed through small pores with gel by an electric field.
DNA is negatively charged, so they move towards the positive electrode.
DNA fingerprinting
uses gel electrophoresis. .
Unique segments of the DNA chain is tagged with a radioactive probe.
Nylon sheet is placed against an x-ray film; black bands will appear where probes have been attached.
The bands are used to compare to samples
Transformation
any process by which foreign DNA is incorporated into the genome of a cell
Vector
delivery system to move foreign DNA into a cell
transgenic
Organisms that have received foreign DNA.
plasmids
bacteria contain this. they are small circular double-stranded DNA in cytoplasm
Used as vectors
Mutations
changes in the sequence of DNA molecule
Point mutations
changes in a single base pair of a DNA sequence.
Silent mutations
a point mutation. no change in amino acids
Missense mutation
a point mutation. results in single substitution of 1 amino acid in polypeptide
Nonsense mutation
a point mutation. converts codon for an amino acid into a stop codon
Gene mutation
changes the amino acids in DNA sequence. May involve more than one base pair
Deletion mutation
1+ nucleotides are removed from the DNA sequence. (gene mutation)
Insertion mutation
an extra nucleotide is placed in the DNA sequence (gene mutation)
frameshift mutations
insertion and deletion gene mutations.
Chromosomal mutations
involves large segments of DNA
Translocational mutation
groups of base pairs move from 1 chromosome to another. Usually occurs between 2 non-homologous chromosomes.
(Chromosomal mutations)
inversion mutation
section of chromosome has reversed its orientation in the chromosome
(Chromosomal mutations)
mtDNA (mitochondrial DNA)
identical to one’s mother, as it is transferred in the cytoplasm of the egg.
Mutations do not occur only in genomic nuclear DNA
