Week 3 Flashcards
Mendelian genetics
Help us discern and predict patterns of inheritance within a family line.
Johann Friedrich Miescher
Coined the term nuclein, now called deoxyribonucleic acid (DNA), the repository for genes.
By 1900, compounds of DNA were known as
Sugar, phosphate groups, nitrogenous bases.
When was the overall structure of DNA was learned?
1953
Deoxyribonucleic acid (DNA)
Long, thread-like molecules with uniform diameter but varied length.
How many DNA molecules are in the nucleus of most human cells?
46 DNA molecules (chromosomes)
How long is an average human DNA molecule?
About 2in long
A single nucleotide consists of.
One sugar- Deoxyribose, One phosphate group, and nitrogenous base.
What are the names of nitrogenous bases?
Adenine (A), Guanine (G) Cytosine (C) Thymine (T)
What pairs with Adenine (A)
Thymine (T)
What pairs with Guanine (G)
Cytosine (C)
A double helix of DNA is shaped like what?
A spiral staircase
How many hydrogen bonds are shared between ( A-T)
Two hydrogen bonds
How many hydrogen bonds are shared between (C-G)
Three hydrogen bonds
The law of complementary base pairing
The base sequence on one strand of DNA determines the base sequence of the other.
What is the previous definition of a gene?
A segment of DNA coding for the synthesis of a specific protein.
Genome
All the genes of one person.
How many genes do humans have?
Around 20,000.
Chromatin
Fine filamentous Material complexed with proteins.
Occurs as 46 chromosomes in most cells.
Histones
Proteins that are crucial for DNA packing. Cluster in groups of eight.
Nucleosome
Core particle
What is the current definition of a gene?
An information-containing segment of DNA that codes for the production of a molecule of RNA that plays a role in synthesizing one or more proteins.
What is the study of whole genomes?
Genomics
Base triplet
The sequence of three DNA nucleotides that stand for one amino acid.
Codon
3-base sequence of mRNA
64 possible codons available to represent 20 amino acids
61 code for amino acids; 3 are stop codons
Start codons
AUG codes for methionine, and begins the amino acid sequence of the proteins.
Stop codons
UAG, UGA, and UAA: signal “end message”
What are the four steps in DNA replication?
unwinding, unzipping, building new DNA strands, and repackaging.
What does DNA unwind from?
Histones
What are the three subphases in interphase?
First gap phase (G1)
Synthesis phase (S)
Second gap phase (G2)
What are the multiple subphases of the Mitosis phase?
Prophase
Metaphase
Anaphase
Telophase
What is (G1) for?
They use that time to grow
What is (S) for?
Cell replication of all nuclear DNA and duplicate centrioles.
(G2)
Cells repair DNA errors, and grow and synthesize enzymes that control cell division.
Mitotic phase
The cell replicates its nucleus and then pinches in two to form new daughter cells.
What is mitosis?
It is the division resulting in two genetically identical daughter cells.
What are some of the functions of mitosis?
1) Developed of an individual from fertilized egg to about 50 trillion cells.
2) Growth of all tissues and organs after birth.
3) Replacement of cells that die.
4) Repair of damaged tissues
What happens during Prophase
The chromatin turns into chromosomes
The nuclear envelope disintegrates
The centrioles start to move to opposite ends and form the spindles.
What happens during Metaphase?
Chromosomes are aligned on the cells equator (middle)
What happens during Anaphase?
Enzyme cleaver two sister chromatids apart at the centromere.
The single strand of daughter cells migrates to the opposite side.
What happens during Telophase?
Chromosomes cluster on each side of the cell.
Rough ER makes a new nuclear envelope around the cluster.
Chromosomes uncoil to chromatin
Mitotic spindle disintegrates
Each nucleus forms nucleoli
Cytokinesis
Division of cytoplasm into two cells
Cyclins
Normally not present, but form during interphase
Cyclin-dependent kinases (Cdks)
Activated by cyclins to phosphorylate other proteins
Cyclin-Cdk complexes control
The replication of DNA and centrioles in the S phase
Heredity
Transmission of genetic characteristics from parent to offspring.
Karyotype
Chart of all 46 chromosomes laid out in order by size
23 pairs of homologous chromosomes
Homologous chromosomes
22 pairs of autosomes
1 pair of sex chromosomes
Females are represented by what combination of chromosomes?
XX
Males are represented by what combinations of chromosomes?
XY
Diploid (2n)
Describe any cell with 23 pairs of chromosomes and somatic cells are diploid.
Haploid (n)
Describes cells containing half as many chromosomes as somatic cells
Human haploid cells contain
23 unpaired chromosomes
Germ cells (sperm and egg cells) are Examples of Haploid or Diploid?
Haploid
Locus
Is the location of a particular gene on a chromosome.
Alleles Loaction
are found at the same locus on homologous chromosomes
Dominant alleles are represented by what?
Capital letter
If a dominant allele is present what happens?
Corresponding traits are usually seen in the individual.
Masks effect of the recessive allele
Often produces protein responsible for visible traits.
What is a Recessive allele represented by?
A lowercase letter
what happens when a recessive allele is present?
The corresponding trait is only seen when recessive alleles are present on both homologous chromosomes.
Ofter codes for the nonfunctional variants of the protein.
Genotype
The alleles an individual possesses for a particular gene.
Homozygous
Individuals have two identical alleles for the gene.
Heterozygous
Individuals have two different alleles for the gene.
Phenotype
The observable trait
Punnett square
A diagram showing possible genotypes and phenotype outcomes from parents of known genotypes.
CC Cc
Cc cc
