Unit 2 SAC 2 definitions Bio

Genes carries code to make a protein

Alleles alternative versions of a gene that arise by mutation on the same place on a chromosome

Genome All the genetic information in an organism; all of an organism's chromosomes.

Homologous chomosomes share the same genes at the same loci, same size+length, same centromere position, one pair from each parent

autosomes Any chromosome that is not a sex chromosome

sex chromosomes One of the 23 pairs of chromosomes in the human, contains genes that will determine the sex of the individual. (X,Y)

chromosome a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

homologous chromosomes carrying same gene loci a matching pair of chromosomes, one from each parent, that carry the same genes at the same loci (locations) but may have different alleles.

Describe the differences in chromosomes vary in number and size between different species, but organisms within the same species usually have the same number and similar-sized chromosomes.

Karyotype A display of the chromosome pairs of a cell arranged by size and shape.

purpose of meiosis To make gamete cells (haploid) for sexual reproduction

haploid gametes Cells with one set of chromosomes (n).

diploid cells A cell containing two sets of chromosomes (2n), one set inherited from each parent.

crossing over chromatids meiosis 1, homologous chromosomes come togtehr and pair up the chromatids twist around each other and bits of chromatids swap over - they still contain the same genes but now have a diff combination of alleles

independent assortment for genetic diversity during meiosis, chromosome pairs separate randomly into gametes, creating different combinations of alleles and increasing genetic diversity.

production of haploid gametes from diploid cells

by the process of meiosis process where one diploid (2n) cell divides to produce four genetically different haploid (n) gametes (sex cells), with half the chromosome number.

zygote/zygosity (whether they are

homozygous dominant, homozygous recessive or heterozygous.) describes the two alleles an organism has for a gene eg: AA, aa, Aa

dominant Describes a trait that covers over, or dominates, another form of that trait.

recessive An allele that is masked when a dominant allele is present

codominance A condition in which both alleles for a gene are fully expressed

complete dominance A type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable. sex linked + autosomal

incomplete dominance neither allele is expressed phenotypically (usually blended)

phenotype An organism's physical appearance, or visible traits.

genotype An organism's genetic makeup, or allele combinations. eg; HH, Hh, hh

'proportionate heritability where an organism's phenotype is explained partly by genes and partly by environmental factors.

the three main influences on phenotype genotype,

environment and epigenetics

patterns of inheritance Various ways traits are inherited from parents to offspring (complete dominance, incomplete dominance, codinmance)

pedigree chart a diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next

autosomal dominant, inheritance pattern of a dominant allele on an autosome

autosomal recessive two copies of an abnormal gene must be present in order for the disease or trait to develop

X-linked dominant an abnormal allele is dominant and occurs on the X chromosome

X-linked recessive a recessive allele located on the X chromosome. Males are more likely to express the trait because they have only one X chromosome, so only one recessive allele is needed.

Y-linked referring to a gene located on the Y chromosome

monohybrid cross A cross between individuals that involves one pair of contrasting traits

monohybrid test

cross used to ID genotype of individual with DOMinant pheotype

meiosis 1 seperates each homologous chromosome into 2 different cells

meiosis 2 seperates each sister chromatid into four different cells

hapolid cell that has only one copy of each chromosome

aneuploidy loss/gain of a single chromosome, caused by non-disjunction

mitosis vs meiosis Mitosis: one division forming 2 identical cells (clones); Meiosis: two divisions forming 4 genetically different cells

non disjunction when chromosomes fail to seperate suring anaphase 1 or 2

non disjunction disorders down syndrome, turner syndrome, klinefelter's syndrome, edwards syndrome

monosomy missing a chromosome (2n-1)

Trisomy extra chromosome (2n+1)

duplications part of the chromosome is copied

deletions part of chromosome is removed

inversions a chromosome mutation where a section of a chromosome breaks off, flips around, and reattaches in reverse order.

translocation part of chromosome is replaced within the chromosome in reverse order

epigenetics the study of environmental influences on gene expression that occur without a DNA change

transcription a sequence od DNA is used to produce a complementory sequence of mRNA

translation an mRNA sequence is used to produce a protein

somatically heritable genetic traits/alterations to a cell inherited by daughter cells during mitotic cell division