How can we help?

You can also find more resources in our Help Center.

44 terms

Biology Exam Review: Genetics and DNA

STUDY
PLAY
fertilization
process in sexual reproduction in which male and female reproductive cells join to form a new cell
allele
one or two more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome
hybrids
the offspring of crosses between parents with different traits
genes
a sequence of DNA that codes for a protein and thus determines a trait
segregation
seperation of alleles during gamete formation
gamete
specialized cell involved in sexual reproduction
probability
the likelihood that a particular even would occur
Punnet squares can determine the gene combinations that might result from a genetic cross
...
homozygous
organisms that have two identical alleles for the same trait (TT or tt)
heterozygous
organisms that have two different alleles for the same trait (Tt)
phenotype
physical characteristics
genotype
genetic makeup
independent assortment
independent segregation of genes during the formation of gametes
incomplete dominance
cases in which one allele is not completely dominant over the over
codominance
both alleles contribute to the phenotype.
multiple alleles
genes that have more than two alleles
polygenic traits
traits controlled by two or more genes
Mendel's Principles
1. the inheritance of biological characteristics is determined by individual units known as genes. Genes are passed from parents to their offspring

2. In cases in which two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive.

3.sexually reproducing animals have two two copies of each gene - one from each parent. They segregate from each other when gametes are formed.

4. Alleles from different genes usually segregate from each other.
homologous
chromosomes that each have a corresponding chromosome from the opposite-sex parent
diploid
a cell that contains both sets of homologous chromosomes

consist of two complete set of chromosomes and two complete sets of genes
haploid
containing only one set of chromosomes therefore containing one set of genes
meiosis
process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.
tetrad
structure containing 4 chromatids that form during meiosis
crossing-over (metaphase)
results in an exchange of alleles between homologous chromosomes and produces new new combinations of alleles
Thomas Morgan Hunt
Mendel's law of independent assortment still holds true but, chromosomes assort independently, not the genes.
gene map
a map showing the relative locations of each known gene on one of the chromosomes
nucleotides
composed of 5-carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base.
nitrogenous bases
adenine, guanine, thymine, and cytosine
prokaryote
a unicellular organism having cells lacking membrane-bound nuclei
eukaryote
an organism with cells characteristic of all life forms except primitive microorganisms such as bacteria
base pairing
only certain hydrogen bonds can form between bases (adenine can only go with thymine and guanine can only go with cytosine)
chromatin
DNA that is tightly coiled around proteins
replication
a process in which each cell will have a complete set of DNA molecules
DNA Replication
1. the DNA molecule separates into two strands
2. it then produces two new complementary strands following the rules of base pairing
DNA polymerase
it joins individual nucleotides to produce DNA molecules. it helps to maximize the odds that each molecule is a perfect copy of the original.
RNA vs. DNA: The Difference
1. the sugar in RNA is ribose instead of deoxyribose
2.RNA is single stranded, therefore no double helix
3. Contains uracil instead of thymine
Types of RNA
messenger RNA, ribosomal RNA, and transfer RNA
mRNA
carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell
ribosomal RNA
type of RNA that makes up the major part of ribosomes
transfer RNA
transfers amino acids to the ribosome as it is specified by coded messages in mRNA
transcription
(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA
RNA polymerase
an enzyme that binds to DNA and separates DNA strands during transcription (unzips the DNA)
promoters
certain regions of DNA that RNA polymerase will bind to in order to split (unzip) the DNA
pleiotropy
A single gene having multiple effects on an individuals phenotype