Chapter 4: Genetics & Cellular Funcution Flashcards
Deoxyribonucleic Acid (DNA)
Double helix
*Spiral staicase
Uniform diameter- 2nm
*length varies
Polymer of nucleotides
Components of DNA
BPD
Bases
- Purines (adenine, guanine)
- Pyrimadines (cytosine, thyamine)
Phosphate Group
Deoxyribose (sugar)
Chromatin
Material that make up chromosomes of organisms
Consists of: RNA, DNA, and proteins
- 46 chromosomes
- 6 ft thread packed in cell nucleus
Histones
Proteins crucial for DNA packing
- Group of 8 molecules
- DNA winds around
Nucleosome
Basic repeating subunits of chromatin
Consist of:
- Histone cluster with DNA around
- Linker DNA- short DNA connecting core particles
Chromatin thrown into complex, irregular loops and coils
Chromosome
A doubled rod of condensed chromatin; contains DNA that carries genetic information.
Chromatids
one of two identical “sister” parts of a duplicated chromosome
Centromere
pinched area where the chromatids of a chromosome are attached
Kinetochore
Protein plaque on the sides of the centromere
Ribonucleic Acid (RNA)
Components? RU
Types?
Single chain- shorter DNA
Interrupts DNA to Synthesize protein
Works in Cytoplasm
Components:
- Ribose (sugar)
- Uracil
Types: mRNA, tRNA, rRNA
Gene
Individual segment of DNA that codes for a specific protein
Genome
All genes of one person
Genetic Code
System that enables these four nucleotides (A, T, C, G) to cods for the amino acids sequence of all proteins
*Minimum code to symbolize 20 amino acid= 3 NT per AA
Base Triplet
Sequence of 3 DNA nucleotides that stand for one amino acid
Codon
The 3-base sequence in mRNA
*65 possible to rep for 20 Amino Acids
Exons
“Sense” portions of the immature RNA
* Will translate to proteins
Introns
“Nonsense” portions of the immature RNA
*Must be removed before translation
Alternative Splicing
Removing the introns by enzymes and splicing the exons together into functional RNA molecules
Translation
3 Stages? Tie
The process that converts the language of nucleotides into language or amino acids
3 Stages:
- Termination
- Initiation
- Elongation
Chaperone Proteins
Older proteins that pick up new proteins and guide them into folding into the proper shape
Mutations & How You Obtain Them
Changes in DNA structure due to replication errors or environmental factors
ex: radiation, viruses, chemicals
Effects of Mutations
Some have no ill effects
Others kill the cell, turn into cancerous, or cause genetic defects in future generations
4 Main Phases of the Cell Cycle
G1: first gap phase
S: synthesis phase(DNA replication)
G2: second gap phase
M: mitotic phase( cell division)
G1: Frist Gap Phase
interval between cell division and DNA replication
*preforms normal functions
S: Synthesis Phase
DNA replication
G2: Second Gap Phase
Interval between DNA replication and cell division
M: Mitotic Phase
Cell division
Mitosis
A body cell doubles its DNA and then divides to produce two genetically identical daughter cells
4 Stages of Mitosis
PMAT
Prophase
Metaphase
Anaphase
Telophase
Prophase
- Nuclear envelope disintegrates
- Chromosomes formed
- Spindel fibers are created
Metaphase
- Chromosomes align on the cell equator
* Spindle fibers attach to the kinetochores
Anaphase
- activation of cleaving enzymes
* spindle fibers pull chromatids to polar sides of the cell
Telophase
- chromatids cluster on both sides an uncoil
- nuclear envelope formed
- spindle fibers disintegrate
Cytokinesis
Division of cytoplasm into two cells
Meiosis
Production of four gametes(haploid cells), each with only half DNA of the diploid cells
Heredity
Transmission of genetic characteristics from parent to offspring
Karyotype
Chart of our 46 chromosomes laid out by size
Diploid(2n)
Any cell with 23 pairs of chromosomes (somatic cells)
Haploid(n)
Contain half as many chromosomes as somatic cells (germ cells)
ex: sperm and egg cells
Locus
Location of a particular gene on a chromosome
Alleles
Different forms of a gene at same locus on two homologous chromosomes
Dominant
Capital Letter
- Masks the effect of any recessive allele present
- Produce protein responsable for visible trait
Recessive
Lower Case Letter
- Expressed only if on both homologous chromosomes
- No dominant allele at locus
Genotype
Alleles that an individual possesses for a particular trait
Homozygous Allele
Two identical alleles for a trait
Heterozygous Allele
Different alleles for that gene
Phenotype
Observable Trait
Carrier
Carry the recessive allele but do not express it
Gene Pool
Genetic make up of a whole population
Codominance
Both alleles are equally dominant
ex: blood type, AB
(both are expressed)
Incomplete Dominance
Phenotype intermediate between traits each allele would have produced alone
ex: skin tone
Polygenic Inheritance
Genes at two or more loci contribute to a single phenotype
ex:eye color
Pleiotropy
One gene produces multiple phenotypic effects
Sex Linked Traits
carried on the X and Y chromosomes
Inherited by one sex vs. the others
ex: color blindness
