CH 4 Flashcards
Mendelian Genetics
Family relationships are analyzed to predict patterns of inheritance in family line
Nucleotide
the basic unit of a nucleic acid composed of a phosphate group, a sugar, and a nitrogenous base
Purine
Adenine, Guanine
Pyrimidine
Thymine, Cytosine, Uracil
Cytogenetics
uses techniques of cytology and microscopy to study chromosomes and their relationship to hereditary traits
molecular genetics
uses techniques of biochem to study DNA structure and function
Genomic medicine
studies the entire DNA of an individual and how it influences health and disease
How many hydrogen bonds to G and C form?
3
How many hydrogen bonds to T and A form?
2
What % of DNA codes for proteins?
2%
Histone
a protein component of chromatin that helps to organize and package DNA
Centromere
the pinched spot that sister chromatids are joined at
tRNA, function
transfer RNA, contains an anticodon, binds amino acids in cytosol and carries them to ribosomes
Essential Function of RNA
to use instructions coded in DNA to synthesize proteins
Gene
information containing segment of DNA that codes for the production of a molecule of RNA and in most cases for 1 or more protein
How many nucleotide pairs in total human genome?
about 3 billion nucleotide pairs
Where is RNA usually found?
In the cytoplasm
Genomics
the study of the whole genome and how genes and noncoding DNA interact
Base triplet
sequence of 3 DNA nucleotides that codes for 1 amino acid
Can multiple codons code for the same amino acid?
Yes
Start codon, what’s it code for?
AUG, methionine
Codon
3 base sequence of mRNA
Translation
the step of protein synthesis in which mRNA is read to make proteins
RNA Polymerase
enzyme that transcribes DNA to make RNA. RNA polymerase opens up DNA helix then transcribes the genetic code to make a corresponding RNA
DNA Polymerase
synthesizes new molecules of DNA
DNA Ligase
joins DNA strands together
Helicase
Unwinds DNA helix during replication
Intron
a portion of pre-mRNA that does not code for protein and that must be removed before translation
Transcription
step of protein synthesis in which DNA is used to make mRNA
Alternative Splicing
one gene can produce more than one protein. Occurs when introns are removed from pre-mRNA
Pre-mRNA
contains introns and exons and cannot leave nucleus until introns and removed and mRNA is formed
mRNA
carries genetic code from nucleus to cytoplasm
Initiator tRNA
1st tRNA to bind to a ribosome in translation. Its anticodon is complementary to AUG (UAC)
3 steps of translation
1) Initiation 2) elongation 3) termination
small & large ribosomal subunits
Small binds to mRNA near lead sequence and moves along mRNA to find start codon. When start codon is reached, large unit joins small and translation begins. initiator tRNA binds to a site, then P, then E as ribosomal unit continues to move along mRNA reading codons
What are the base pairings of RNA?
U-A, A-U, G-C, C-G
Base pairings of DNA?
T-A, A-T, G-C, C-G
Polyribosome
term for cluster of ribosomes attached to one mRNA during translation
Chaperone Proteins
aid a newly synthesized protein in folding to its proper shape, help prevent improper association with other proteins. Some are also know as stress and heat proteins because they help repair proteins damaged by either heat or stress to the cell.
Where are proteins that are secreted from the cell or packaged into lysosomes synthesized?
on the RER not free ribosomes. mRNA travels to RER where it docks onto the surface and that’s where translation takes place
Postranslational Modificiation
carbohydrates may be added to the protein, it may involve removal of some amino acids, the protein may be folded and stabilized by disulfide bridges
Proteins that remain in cell after being synthesized
Histones and actin
Replication
process by which a cell makes a copy of its DNA producing 2 new daughter strands
Semiconservative Replication
DNA replication produces 2 daughter DNA each with 1 new and 1 old helix conserved from parental DNA
DNA Polymerase function
Detects and corrects errors in DNA replication, this happens in cell cycle G2
Cell Phases
g1, S, g2, M (g0)
g1
interval between cell division and DNA replication in which a cell synthesizes proteins, grows, accumulates the materials needed to replicate DNA in next phase
S
cell makes a duplicate copy of its DNA and centrioles
g2
short period of time of growth and preparation for mitosis in which cell produces enzymes that control cell division, and checks and repairs the newly copied DNA
M
cell replicates its nucleus and forms 2 new daughter cells
g0
cells are in a non-dividing phase outside of the cell cycle
Steps of Mitosis
Prophase, Metaphase, Anaphase, Telophase
Prophase
chromosomes condense, nuclear envelope disappears, spindle fibers grow, centrioles migrate to the poles of the cell
Metaphase
chromosomes align along the center of the cell
Anaphase
Daughter chromosomes migrate to opposite polls of the cell
Telophase
Chromosomes are gathered at the poles, chromatin decondenses, new nuclear envelope forms, new nuceloli appear, and the spindle fibers vanish
Mitotic Spindle
the lemon shaped array the spindle fibers form during metaphase, shorter microtubules form a starlike aster that anchors the spindle to the inside of the plasma membrane
Cytokinesis
division of the cell’s cytoplasm into 2 cells
Heredity
transmission of genetic characteristics from parent to offspring
Homologous Chromosomes
pairs of chromosomes that are the same size and shape and code for the same information (one from each parent)
Cyclins & Cdks
Cyclins and cyclin dependent kinases that help regulate the cell cycle
X & Y chromosomes
Sex Chromosomes
All other chromosomes
Autosomes
Karyotype
chart the organizes chromosomes in order by size and other physical features
Haploid
23 unpaired chromosomes, sperm & egg cells
Diploid
23 pairs of chromosomes, all cells in body except sperm & egg cells
Somatic Cells
all cells of the body except sperm and eggs
Germ cells
sperm and egg cells
3 specific points in cell cycle that a cyclin binds to a Cdks
During g1, late in g2, end of metaphase
Locus
location of a specific gene on a chromosome
Allelels
alternative forms of a gene
Heterozygous
Different alleles found at a loci on homologous chromosomes
Homozygous
identical alleles at a loci on homologous chromosomes
Carrier
a person who has a recessive allele that is not expressed phenotypically
Genotype
refers to the alleles a person possesses for a trait
incomplete dominance
inheritance of a trait in which a heterozygote has an intermediate expression between either allele
Polygenic inheritance
traits determined by genes at multiple loci. traits like eye and skin color. Determined by 2 or more genes
Pleiotropy
one gene that has multiple phenotypic expressions
Multiple allele inheritance
3 or more alleles exist for the same gene
Why are men more likely to be color blind?
Color blindness is a sex linked, recessive trait, it is found on the x chromosome. Females have 2 x chromosomes so even if one chromosome contains the recessive allele, it is very likely that the other x chromosome will have the dominant allele and mask the trait. Since males only have 1 X chromosome, they will phenotypically display whatever allele they inherit for any sex linked trait, there’s no chance of the allele being masked.
Codominant trait
both alleles of a heterozygote are expressed
Type O Blood
people with type O blood are homozygous for this recessive allele
Red flower crossed with white flower produces pink flower. What is this an example of?
Incomplete dominance
Penetrance
the percentage of a population with a given genotype that actually exhibits the predicted phenotype
What do genes need to produce a phenotypic effect?
Nutritional and environmental input
Epigenetic Effects
alter gene expression, reversibly activating and silencing genes without changes in base sequence
Genetic Code
pattern of nitrogenous bases that represents the 20 amino acids of a protein
Growth factors
chemical that signals cells to divide
