ECHS Inheritance

what is inheritance

the act of passing on traits to offspring

what is the biological basis for inheritance

genes - segments of DNA that code for proteins

chromosome disorders are caused by nondisjunction. what does this mean

failure of homologous chromosomes to separate properly during meiosis 1 and meiosis 2

what is the result of nondisjunction

gametes with an abnormal number of chromosomes which can lead to a disorder of chromosome numbers

what are some examples of chromosomal disorders

• partial deletions/duplications - part of the chromosome is deleted/duplicated

• inversion - one segment dissociates, inverts, and reattaches to the original location

• translocations - one segment of a chromosomes dissociates and reattaches to another

what is a genome

a full set of genetic information that an organism carries in its DNA

what is a chromosome

the bundles of DNA and protein found in the nucleus of eukaryotic cells

how can we see chromosomes clearly

calls are photographed during mitosis when chromosomes are fully condensed and easy to view

what is a karyotype

when chromosomes are cut from the photographs and arranged into a picture known as a karyotype

how many chromosomes total are found in a human cell

46

how many pairs of chromosomes are found in a human cell

23 pairs

what can we learn by viewing karyotypes

• sex of a child

• missing/extra chromosomes

• chromosomal abnormalities

which chromosomes are autosomes

22 pairs of the 44

which chromosomes are sex chromosomes

1 pair or 2 total

what is the sex chromosomal combination of males and females

xx is female and xy is male

define genetics

the scientific study of heredity

define heredity

the passing down of traits from parents to offspring via genes and chromosomes

who is known as the father of genetics

gregor mendel

what type of organism did he use to study different traits

the garden pea

what are different forms of a gene called

alleles

an individual characteristics, known as traits, are determines by factors called what?

genes

what is the first point in mandel’s 5 point hypothesis

1. each trait is determined by a gene. each organism has 2 alleles for each gene on each homologous chromosome

what is the second point in mandel’s 5 point hypothesis

2. when 2 different alleles exist in an organism

• dominant - masks the expression of the other

• recessive - need both alleles to be the same

what is the third point in mandel’s 5 point hypothesis

pair of alleles segregate from each other, each gamete receives one - law of segregation

what is the fourth point in mandel’s 5 point hypothesis

chance determines which alleles goes where

what is the fifth point in mandel’s 5 points hypothesis

true breading organisms have two copies of the same allele - homozygous

how many alleles do we have from each parent

one

what are the three possible combination of alleles

(TT) homozygous dominant, (Tt) heterozygous hybrid, (tt) homozygous recessive

punnett square

uses probability to help predict traits

probability

likelihood of offspring

genotype

combination of alleles (TT, Tt, tt)

phonotype

apperance of a trait (tall, short)

______ are passed from _______ to _______

genes; parents; offspring

what is the law of dominance

at least 1 dominant allele in a pair may mask the other allele, preventing it from having an effect

what is the law of segregation

two alleles seperate during the formation of sex cells, so that each gamete carries only one allele from each gene

what is the law of independent assortment

alleles for different characteristics are distributed independently and randomly to gametes or sex cells

what is a test cross

it is used to determine if an organism is homozygous or heterozygous for a dominant trait

what is a dihybrid cross

a cross (or mating) between 2 organisms where 2 genes are studied. the genes are located on seperate chromosomes, so the traits themselves are unrelated

what are some of the exceptions to mendel’s principles

incomplete dominance, codominance, multiple alleles polygenic traits, pleiotrophy, environmental influences, sex influenced traits

what is the pattern of incomplete dominance

neither allel is completely dominant over the other

what is the result of incomplete dominance

a third intermediate phenotype for heterozygous genotype

what is an example of codominance

red and white flower - RW = pink

what is the pattern of codominance

phenotypes for both alleles are expressed equally

what are two examples of codominance

ab blood types and speckled chickens

explain the pattern of multiple alleles

a gene wiht more than 2 alleles said to have multiple alleles

what does a ploygenic traits mean

many genes

continuous traits, traits controlled by 2 or more genes

explain this pattern of polygenic trait

what is the result of polygenic traits

wide range of phenotypes and ditribution among population

what is pleiotrophy

when a single gene can have mulitple phenotypr effects

what is an autosomal trait

chromosome that is not influeneced by sex

where are most sex linked traits found

on the x chromosome

what is pedigree

a graphic representation of an individual’s family tree

What do the following represent in a pedigree

circle is female

square is male

vertical line and bracket is connecting parents to children

horizontal lines is mariage

shaded has the trait and expressesit

half shaded is a carrier of a trait

what is biotechnology

use and alteration of organisms, cells, or biological molecules to produce food, drugs, or other goods

explain selective breeding

allowing only those with wanted characteristics to produce the next generation. takes advantage pf naturally occuring genetic variation to pass traits on to the next generation

what is hybridization

crossing dissimilar organisms to bring together the best of both organisms

what is inbreeding

the continued breeding of individuals with similar characteristics

what is genetic engineering

the process of making changes in the DNA code of a living organism

how can dna be manipulated

by using traits that can cut, separate, and then read dna base by base, scientists can now read the base sequences in dna from any cell

what are restrict enzymes

highly specific substances cut dna into restriction fragments

what is recombinant dna

a gene from one organism can be attached to the dna of another organism

what are sticky ends

restriction enzymes cut dna at specific sequences, producing single-stranded of overhangs of dna

what enzyme is responsible for joining dna fragments together

dna ligase

how are transgenic organisms produced

produced by the insertion of recombinant dna into the genome of a host organism

what is a clone

a clone is produced from a single cell- a member of application of genetically identical cells produced from a single cell