Genetics/ Forces of Evolution Flashcards
Darwin and Inheritance
the transfer of genetic sequences from one generation to the next
blending inheritance
The notion that traits are inherited like different colors of paint blend
Gregor Mendel
- palacky university of olomouc, university of vienna
- botanist
- augustinian friar
- relationships between breeding and traits
- father of genetics
Mendel pea experiment
- a series of experiments that involved cross-pollinating pea plants with different traits to study how traits are passed down through generations
- Flower colour, Flower position, Plant size, Pod colour, Pod shape, Seed colour, and Seed shape
- Creating a parent generation of true-breeding plants
Breeding two parent plants to create a second generation of plants (F1)
Self-pollinating two F1 plants to create a third generation (F2) - important for understanding inheritance
gene
segment of chromosomes in DNA (nitrogen bases that specify the sequence of amino acids in proteins) that codes for protein or trait
allele
alternative form of a gene at a particular locus of homologous chromosomes
different expressions of a trait are controlled by alleles that occur in pairs
genotype
what alleles an individual has
phenotype
what trait is expressed in an individual
law of segregation
one copy of a gene (an allele) in inherited from each parent (at random)
i.e., each parent flower has 2 alleles for the flower colour gene, each offspring will inherit one allele from each parent
law of independant assortment
the alleles of different genes are passed on independently of each other
i.e. the alleles for the genes controlling flower colour and seed colour are passed down independently of one another
homozygous
two copies of the same allele for a gene
heterozygous
two different allele genes
dominant
always expressed allele
recessive
not expressed in presence of a dominant allele
punnett square
- tool for sorting alleles
- investigate relationship between parent and offspring genotypes and phenotypes
inheritance 1940
- genes are known to be discrete units of heredity
- variants of genes
inheritance 1944
DNA identified as the transforming principle by oswald avery
inheritance 1952
rosaind franklin images DNA using Xray crystallography techniques
DNA
- double helix
- double stranded
- chains of nucleotide; phosphate, sugars (deoxyribose), nitrogen bases (adenine, theymine, guanine, cytosine)
- very long
base pairing
A-T
G-C
- joined by hydrogen bonding
- the order of the bases code for certain messages (genes)
RNA
-Ribose
- single stranded
- four base pairs (adenine, uracil, guanine, cytosine)
- allows for expression of genes via codons
- they carry messages in DNA outside the nucleus for protein synthesis
genome
- full compliment of genes/DNA for an organism
- not all parts code for proteins: there are coding sequences and non-coding sequences
- non-coding sequences are still functional (ex. regulatory genes turn on/off genes that do code for proteins)
- unique to an individual
genetic code
- information encoded in genetic material
- translated and expressed as proteins
autosomes
- numbered homologous pairs
- one from each parent
sex chromosomes
- X chromosome
- Y chromosome
- one from each parent
karyotypes
- a visual representation of an individual’s chromosomes, which shows their number, structure, and size
- humans have 23 pairs, 46 total (22 pairs autosomal, 1 pair sex
- there is variation in chromosomal types and number
- sex ≠ gender
the building blocks of life
- cells are the basic units of all living organisms
- a cell is the most primitive and basic form of life on earth
prokaryotes
- single cell organism (ex. bacteria)
eukaryotes
- complex cell with nucleus
- found in all multicellular organisms
- can be divided into two types: somatic and gametes
somatic
- make up bodys organs and tisssues
- reproduce through mitosis
- diploids (two copies of chromosomes)
gametes
- reproductive cells
- fuse during sexual reproduction
- haploids (one copy of each chromosome)
- produced though meiosis
what are cells made up of
- cell membrane
- cytoplasm
- organelles
- nucleus
nucleus
- DNA
- RNA moves in and out
- stores genetic information in the form of DNA
organelles
- endoplasmic reticulum
- ribosomes
- mitochondria
ribosomes
- function in protein synthesis
mitochondria
- energy producers
- endosymbiosis
- mitochondrial DNA (fast evolution)
nuclear DNA
- an organisms genetic information
- blueprint for an organism and the same in all somatic cells within an individual
chromatin
DNA when it is wound up into chromosomes
chromatid
one arm of a chromosome, joined to its sister by the centromere
DNA replication
- DNA is unzipped by helicase enzyme
- exposing nitrogen bases
- each strand acts as a template for a new strand: complementary pairing and duplication
cell division
- the process by which new sells are created, occurs in the nucleus
mitosis
- 46 chromosomes line up
- interphase, prophase, metaphase, anaphase, telophase and cytokinesis
replication
- dna replication
- sister chromatid chromosomes line up
- spindles form
- pull apart into two daughter cells
- 2 identical diploid cells are left when done
meiosis
- gamete-forming cell with 46 single-chromatid chromosomes
- similar to mitosis, but recombination/crossing-over occurs and there are 2 divisions
- 4 non-identical haploid cells
recombination
- crossing over
- formation of unique daughter cells from parent cells
reduction division
random assortment, enhances genetic diversity
protein synthesis
- proteins are composed of amino acids, coded for by codons (3 nucleotide sequences in genes)
DNA (genes)>RNA (codons)>amino acids>polypeptide chains> proteins
transcription
-mRNA copies message from DNA
translation
rRNA reads the message in the mRNA (codons)
assembly
tRNA brings corresponding amino acids
mendalian traits
- discrete traits
- controlled by one gene
polygenic traits
- continous variation
- phenotype determined by action of more than one gene
- environment may also contribute
epigenetics
- DNA interacts with environment to influence appearance, behaviour, function
- environmental influences on gene expression
- ex. dutch famine
what are the forces of evolution
natural selection, mutation, genetic drift, gene flow
mutations
- create new variation in population
- can be harmful (delterious), neutral or beneficial
- natural selection acts on variation
point mutation
- substitution: substitution of a single base
- frameshift mutation: insertation or deletion
chromosomal deletion
when a part of a chromosome is lost
chromosomal duplication
DNA segment is duplicated, resulting in extra copies of a chromosomal region
chromosomal inversion
a rearrangement of a chromosome that occurs when a segment of DNA breaks off and reattaches in the same chromosome, but in the opposite orientation
chromosomal insertion
involves the addition of one or more nucleotides into a segment of DNA
chromosomal translocation
- usually lethal
- when a chromosome breaks and reattaches to another chromosome, or when pieces from two chromosomes trade places
population genetics
change in population and gene pools
genetic drift
- changes in gene frequencies due to random sampling from one generation to the next
- effects are greater when population size is smaller
- not directional, unpredictable, not adaptive
- can reduce genetic diversity
bottleneck effect
- reduction in variation due to random influence
- population passes through a ‘bottleneck’ changing gene frequencies
founder effect
- random, unintentional
- when a small group of individuals from a larger population become separated and form a new population
gene flow
- movements of genetic elements between different populations; migration, multiple populations, exchange, not always unidirectional
hardy-weinberg equilibrium
- mathematical equation describing stability in genotype and allele frequencies between generations
- describes the proportion of a pair of alleles in a population
assumptions
- random mating
- no natural selection
- no gene flow
- no genetic drift
- no mutation
- when assumptions are not met, a change in allele frequencies occurs = evolution
