Genetics Flashcards
what is a centromere and the 4 major types
- metacentric- middle
- submetacentric- centromere toward one end
- Acrocentric- very close to end
-Telocentric- very tip of arms
gene
hereditary units that control particular characteristics/ traits
genotype vs phenotype
phenotype- The trait that is expressed. E.g. Bb but have black hair appearance
genotype- the pair of alleles E.g Bb
allele
different form of gene represented via symbols
Types of chromosomes
- Autosomes (somatic) (1-22)
- Allosomes (gametes) (23)
Ploidy
number of chromosome sets that a cell carries
- haploid ( half)
- diploid
Homologous chrom vs non homologous chrom
homologus- identical pairs of chromosomes
- carry the same genes but not the same versions of gene e.g mum and dad one brown and one blonde
- non homologus- different chromosomes that carry different genes
Karyotype
visual representation of chrom
what are chromosomes counted by
centromere
Meiosis
only occurs in eukaryotes
allows for genetic variability vis genetic recombination and crossing over
- is a reduction division resulting in 4 haploid daughter cells
genetic variations in gametes
- random crossing over during prophase 1
> genes from non-sister chromatids are swapped
> creates gametes with unique chrom - Independent assortment during metaphase 1
> homologus chroms line up @ equator RANDOMLY
what is a loci/locus
the specific location of a gene on a chromosome
what does DNA stand for
Deoxyribonucleic acid
DNA definition
- is a complex molecule that contains all the genetic info necessary to build and maintain an organism
what are the nitrogenous base for DNA and RNA
DNA- ATGC
RNA- AUGC
- cytosine, adenine, guanine, thymine
DNA structure
-sugar phosphate backbone
- DNA is made up of building blocks called nucleotides
- DNA is coiled around histones( protein that provides structural support)
structure
Bases > Nucleotide > DNA > Nucleosomes > Chromosomes
nucleotide structure
- purines- double ring DNA structure
- Pyramidines- single ring
DNA vs RNA
r- single stranded DNA
- diff nitrogenis base Uracil replaces thymine
- present during DNA rep
d- two strands anti parrelel
5’-3’, 3’-5’
impacts on Phenotypes
- genotypes and environmental influence
enviro influence
The environment can change gene expression and therefore the phenotype.
Epigenetics
- The study of how the environment changes gene expression (how the environment changes the phenotype)
Types of phenotypes
co dominance
> both alleles are equally expressed
e.g r,w, roan cow (rw)
incomplete dominance
> become blend e.g r ,w , pink
chaisma
point of crossing over on a chrom
define recombination
The crossing over of chromosomes during Prophase - chromosomes swap alleles to create recombinant gametes
define monosomy
having on less chrom (45)
define gene linkage
pedigree patterns
x linked dom -
x linked recessive -
autosomal dom- two affected parents with not all children affected
autosomal recessive- two unaffected parents w affected child
crossing over
during first division in meiosis. Produces chromosomes with new combos of genetic info
recombinant chromatids
after crossing over where some of the chromosomes have new combos of gene (mum and dad)
meiotic cell division
- Interphase before meiosis occurs DNA is replicated, chromosomes duplicate, result in two identical sister chroms
- P1- condens, plump and visible
- M1- line up in the middle (equator), arranged independently(indep assortment), spindle fibres attach to centromere
- A1- spindles shorten and pull the chroms apart
- T1Cleavage furrow is formed as two separate nuclei form
6 cytokinesis 1 2 haploid daughter cells - P2 SPINDLE FIBRES ARE RECREATED
- duplicated chroms line up in middle, spindle fibres attach to centromere
- A2 spindles shorten separating sister chromatids
- T2 cleavage furrow formed
- 4 haploid daughter cells
trisomy
additional chrom (47)
trisomy 21
down syndrome
-flat face, short neck, tonge tends to stick out
trisomy 13
patau syndrome
- intellectual disability, cleft lip/palate
trisomy 23
k linefelter syndrome
- male carries 2 X chroms (XXY)
-tall, shorter torso, absent/ delayed puberty
monosomy 23
- female only carries one x
- short, infertile
