Exam 3

Biology 150l.3 with Holloway at Massachuetts College of Pharmacy & Health Sciences

About this deck

By: Carissa DiPietro
Textbook: Biology AP* Edition
Created: 2011-11-15
Size: 89 flashcards
Views: 31

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Gene

A discrete unit of hereditary information consisting of a specific nucleotide sequence

Locus

A genes specific location along the length of a chromosome

Autosomes

A chromosome that is not directly involved in determining sex, not a sex chromosome (22 sets in humans)

Sex Chromosomes

X and Y chromosomes; a chromosome responsible for determining the sex of an individual (1 set in humans)

Sister Chromatids

Either of two copies of a duplicated chromosome attached to each other by proteins at the centromere

Homologous Chromosomes

Two chromosomes of the same length, centromere position, and staining pattern in a karyotype

Somatic Cells

Any cell in a multicellular organism that is not an egg or sperm cell

Gametes

Contains a single set of chromosomes and is haploid; egg or sperm cell

Diploid Cell

Has two sets of chromosomes. Human diploid number is 46

Haploid Cell

Single chromosome, egg or sperm cell. Human haploid number is 23

Prophase I

DNA tightly coils, individual chromosomes become visible. Homologous chromosomes become closely associated in synapsis and exchange segments via crossing over

Metaphase I

Nuclear membrane disappears and microtubules form a spindle. Homologous pairs line up on metaphase plate

Anaphase I

Microtubules of spindle fiber shorten and pull the chromosomes toward the poles. Each pole ends up with a complete haploid set of chromosomes consisting of one member of the homologous pair.

Telophase and Cytokinesis I

Nuclear membrane reforms around the daughter nuclei. Each daughter nucleus contains two sister chromatids for each chromosomes. Because of crossing over, sister chromatids are not identical.

Prophase II

Nuclear envelope breaks down and a new spindle forms

Metaphase II

Spindle fibers bind to both sides of the centromeres

Anaphase II

Spindle fibers contract and sister chromatids move to opposite poles

Telophase and Cytokinesis II

Nuclear envelope reforms around the sets of daughter chromosomes

Synapsis

Process by which homologous chromosomes line up and become physically connected in prophase I

Chiasma

Cohesion location where crossing over occurs

Crossing Over

Reciprocal exchange of genetic material between non-sister chromatids during prophase I of meiosis

Tetrads

Formed by homologous chromosomes undergoing crossing over between non-sister chromatids, group of four closely associated chromatids of a homologous pair formed by synapsis

Karyotype

Image of chromosomes arranged in pairs, starting with the longest chromosomes. Can be used to check for abnormalities (i.e. Down Syndrome)

Independent Assortment

Homologous pairs orient randomly at metaphase I of meiosis. Each maternal/paternal pair aligns independent if all others. Number of possible combinations = 2^n where n = haploid number (i.e. humans = 2^23

Crossing Over

Produces recombinant chromosomes. Begins early in prophase I. Homologous portions of non-sister chromatids trade places

Random Fertilization

Any sperm can fuse with any egg. Occurs at random between any two contributing individuals

Recombinant Chromosomes

Combination of genes from both parents in one chromosome. The result of crossing over

Zygote

Fertilized egg which contains one set of chromosomes from each parent and is therefore diploid

Alleles

Different versions of genes that produce distinguishable phenotypic effects.

Mendel's First Law - Law of Segregation

1. Alternate versions of heritable traits exist (alleles)

2. Two alleles are inherited for each trait, one from each parent (same-true, different - hybrid)

3. If alleles at a locus differ then one allele is dominant and one is recessive

4. The two alleles for a trait separate during meiosis (sperm/egg receive either of the two alleles)

Mendel's Second Law

Separate genes for separate traits are passed independently of one another from parents to offspring. Alleles of different genes sort independently of one another during gamete formation.

True-breeding

Parents with a specific phenotype produce offspring with only that phenotype

Hybrids

Cross fertilization of two different things results in an f1 generation (hybrid)

P generation

Parental generation

F1 Generation

1st generation (hybrids)

F2 generation

F1 individuals self pollinate and make f2 generation

How traits, genes, and alleles are related

Alleles are different versions of DNA. Alleles make up a genotype which determines traits of a person (phenotype)

Genotype

The set of alleles that determines the expression of a particular trait

Phenotype

Physical appearance/expression of trait based on a specific genotype

Dominant Allele

Uppercase

Recessive Allele

Lowercase. "Heritable trait" Can appear in later generations even if it is not physically present in prior generations

Heterozygous

Homozygous

AA or aa

Dyhybrid Cross

9:3:3:1 ratio

Monohybrid Cross

1:1 ratio or 1:2:1 ratio

Test-cross

How to determine the genotype of an individual with the dominant phenotype (can be two different genotypes). The test-cross breeds unknown dominant and homozygous recessive.

Pleiotrophy

When a gene effects multiple phenotypes

Complete Dominance

Occurs when phenotypes of the heterozygote and dominant homozygote are identical

Incomplete Dominance

One allele for a specific trait is not completely dominant over the other. This results in a combined phenotype (i.e. red flower + white flower = pink flower)

Codominance

Two dominant alleles of the same gene affect the phenotype in separate, distinguishable ways (i.e. AB blood type)

How does dominance relate to phenotype

Dominance is automatically expressed

Multiple Alleles

Increase the amount of alleles in the gene pool but a person can still only get two of the alleles

Blood Types

A - IA IA or IAi

B - IB IB or IBi

AB - IA IB

O - ii

Epistasis

Another gene changes the phenotype regardless of genotype. Can effect the phenotypic ration (i.e. albino rats)

Polygenic inheritance

Indicated an additive effect of two or more genes on a single phenotype. A single trait is controlled by two or more alleles (i.e. skin/eye color)

Multifactorial traits

Genetic and environmental factors collectively influence phenotype (i.e. diabetes, mental disorders, cancer, heart disease)

Chromosomal Theory of Inheritance

Genes are located on a chromosome and the behavior of chromosomes during meiosis accounts for inheritance patterns. Created by Thomas Hunt Morgan

Relation between Mendelian genes and Chromosomal Theory

Mendelian states that traits are inherited, chromosomal theory states how those genes are inherited

Autosomal Dominant

Appears in every generation

Every affected individual has at least on affected parent

Normal individuas can never transmit the trait

Two affected individuals can have an unaffected child.

Autosomal Recessive

Does not appear in every generation. Carriers are people that carry a recessive allele that doesn't make them sick, but they can pass it on to their offspring.

All children of two affected parents are affected

X-linked Dominant

Affected fathers give the trait to all daughters

Affected sons must have an affected mother

X-linked Recessive

Affected mothers will transmit the trait to all sons

Males are much more likely to be affected than females

Y-linkage

Sex linked trait that is only transferred from male to male, never affects a female.

Wild type

Gene that is most commonly found in a population, denoted by a '+'

Mutant

A gene that has changed so that the normal transmission and expression is affected

Linked gene

Any pair of genes that tend to be transmitted together, usually located very close together on the same chromosome, All genes on a chromosome; however, are not necessarily linked. Morgan worked with linked genes in his experiment

Unlinked gene

Genes that sort independently. The genes are located on different chromosomes or so far apart on the same chromosome that it is highly likely the two will be separated by crossing over. Mendel worked with unlinked genes in his experiment

Parental type

An offspring with a phenotype that matches one of its parents phenotypes

Recombinant

An offspring in which genetic recombination has taken place (opposite of parental type)

Recombination frequency

Number of recombinants divided by the total number of progeny. The further apart two genes are, the higher the recombination frequency

Genetic linkage

When a pair of genes are close enough that they are unlikely to be separated by crossing over, they are genetically linked

Physical linkage

When two genes are on the same chromosome, they are physically linked

Sex chromosomes in Humans

X and Y

Females are XX

Males are XY

X chromosome carries more information because...

It has more genes than the Y chromosome (2,000 vs. 47-58) The X gene is also larger

Aneuploidy

Abnormal number of a particular chromosome; fertilization of gametes in which nondisjunction occurs

Nondisjunction

Homologous chromosomes do not separate normally during meiosis. Can occur in anaphase I (tetrads don't separate properly) or II (sister chromatids don't separate properly) Nondisjunction occurs more frequently in women due to the aging of the eggs. Gives way to monosomic or trisomic gametes

Polyploidy

An organism has more than two complete sets of chromosomes (XYXY) usually results in death of the organism

X inactivation

Phenomenon in a female by which one x chromosome is randomly inactivated. Also occurs in males with Klinefelter's syndrome who have more than one X chromosome. X inactivation is important because if it didn't occur women would have twice as many proteins encoded by x chromosome genes which would result in death

Barr body

Condensed, inactivated x chromosome in most female mammals. Verifies individual is genetically female

In calico cats, the sooner X activation occurs the bigger the spots

Hemizygote

Diploid cell or organism in which only one allele is present for a particular gene

Sex linked disorders are more common in...

Males, because there is only one x therefore (unlike in most females) there is no addition x chromosome to counteract an affected chromosome.

Sex linked disorders

Turner's, Muscular dystrophy, hemophilia

Monosomic

A zygote which has one less than the normal diploid number of chromosomes (2n−1)
Do not usually develop to term (exeption - Turner Syndrome)

Trisomic

Zygotes containing an extra chromosome (2n+1)

Usually develop but with severe abnormalities

Aneuploidy Autosomal Disorders

Trisomy 21 - Down's Syndrom (45 + XY) or (45 + XX)

Trisomy 13 - Patau Syndrome

Trisomy 18 - Edward Syndrome

Aneuploidy of Sex Chromosomes

Turner's Syndrome (44 + X) or (44 + Y)

Kleinfelter's Syndrome (44 + XXY) or (44 + XXX)

Four types of chromosomal restructuring

Deletion- part of chromosome is missing

Duplication - part of chromosome is duplicated

Inversion - parts of chromosome change places

Translocation - Crossing over between non homologous chromosomes that are not normally supposed to pair up with each other

Chronic Myelongenous Luekemia (CML) is caused by translocation of chromosomes

Disorders arising from restructuring of chromosomes

Deletion in chromosome 4 : Wolf Hirshhorn

Deletion in chromosome 22 : DiGeorge Syndrome

Deletion in chromosome 5 : Cri du Chat

Philadelphia Chromosome

a specific chromosomal abnormality that is associated with chronic myelogenous leukemia (CML). It is due to a translocation of genetic material between chromosome 9 and chromosome 22. 95% of people with CML have this abnormality

About this deck

By: Carissa DiPietro
Textbook: Biology AP* Edition
Created: 2011-11-15
Size: 89 flashcards
Views: 31

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj