UNIT 2

what are the Two main types of cells?

Based upon organization of -genetic material Prokaryotic cells -lack membrane-bounded nucleus Eukaryotic cells - have nucleus housing DNA All types of cells have a cell membrane

Changes in chromosome structure

Due to breakage Possible changes include - deletion duplication translocation inversion

Deletion

When a single break causes a chromosome to lose an end or 2 breaks result in the loss of an internal segment Williams syndrome chromosome 17 loses a tiny end piece Cri du chat chromosome 5 loses an end piece

Codominance

When an individual is heterozygous for such traits, the resulting phenotype or expression of these two traits is not blending, because both traits are expressed individually. In horses, chestnut and cremello (almost) white coat colors are codominant. Heterozygous horses have a blend of both colors, a golden tan color with lighter manes and tails . Such heterozygous horses are known as palominos (like Mr. Ed).

Multiple-allele traits

When more than two different alleles exist -for the same trait A, B, O, Blood Groups Each person has only 2 of the -3 alleles Both IA and IB are dominant to i IA and IB are codominant - both will be expressed equally in the heterozygote Inheritance of ABO blood type Type A = IAIA, IAi Type B = IBIB, IBi Type AB = IAIB Type O = ii

Both plants & animals need mitochondria to - a. produce glucose. b. produce ATP. c. produce lipids. d. breakdown protein. e. manufacture phospholipid.

b. produce ATP.

A woman with Type AB blood marries a man with Type B blood. If they have children, what are all the possible blood types for these individuals? a. AB only b. AB, AA, AO, and c. AB, BB, AO, and BO d. BB only e. AA, BB, and AB

c. AB, BB, AO, and BO

Which of the following human cells would contain cilia? a. red blood cell b. sperm c. cell from the trachea (windpipe) d. neuron e. bone cell

c. cell from the trachea (windpipe)

A known abnormality in a gene's sequence that can be linked to a genetic disease is called a(n) - a. genetic profile. b. enzyme. c. genetic marker. d. DNA microarray. e. genomic DNA.

c. genetic marker.

What must materials pass through to enter or leave a cell? a. ribosome b. nucleus c. plasma membrane d. lysosome e. vacuole

c. plasma membrane

Karyotype

photo of chromosomes Autosomes Pairs 1 - 22 Sex chromosomes Pair 23 XX XY

Pre-implantation Genetic Diagnosis

Test embryos for genetic diseases Following IVF, 1 cell can be removed from embryo without harm Test embryos for sex selection

Gregor Mendel

"Father of Genetics"

Turner syndrome (45, XO)

Absence of second -sex chromosome Female

what is the Cell theory?

All organisms are composed of cells All cells come only from -preexisting cells

Genotype

Alleles individual receives at fertilization Homozygous - 2 -identical alleles Homozygous -dominant Homozygous -recessive Heterozygous - 2 - different alleles

Receptor proteins

Allow signal molecules to bind, causing a -cellular response insulin Diabetes mellitus Insulin produced by the pancreas Binds to receptor protein Allows uptake of glucose from the blood stream

Alleles

Alternative forms of a gene Alleles are located on -homologous chromosomes

Lysosomes and apoptosis

Apoptosis = programmed cell death Ex. Tadpole tail, fingers during human embryonic development Syndactyly 1/2000 births Disappears at 4 months gestation

Mitochondria

Break down carbohydrates to produce adenosine triphosphate (ATP) Found in BOTH plants and animals

Ribosomes

Carry out protein synthesis in -the cytoplasm Composed of - 2 subunits Some ribosomes free in cytoplasm Many attached to endoplasmic reticulum

Mitosis

Cell division - replication of - Growth Replacement Repair Outcome Daughter cells identical to diploid parent cells

Energy related organelles

Chloroplasts Use solar energy to synthesize carbohydrates Only in plants and -some protists

Endomembrane system

Consists of nuclear envelope, membranes of endoplasmic reticulum, Golgi apparatus, and vesicles Transport vesicles carry molecules from one part of the system to another

Enzymatic proteins

Directly participate in metabolic reactions lactase Lactose Intolerance Lack of lactase -Cell membrane enzyme Lactose reaches large intestine Diarrhea Gas Bloating

Mendel's Law of Independent Assortment

Each pair of factors segregates (assorts) independently of the other pairs All possible combinations of factors can occur in -the gametes

PGD - Designer Babies?

Embryos are tested for defective genes Will this lead to eugenics?

Klinefelter syndrome (47, XXY)

Extra X Male

Counseling for Chromosomal Disorders

Genetic counseling - potential parents are advised on their risk of inherited disorders Karyotyping - visual display of chromosomes arranged by size, shape, and -banding pattern Can be from white blood cells or fetal cells by amniocentesis or chorionic villus sampling

Autosomal Dominant Disorders

Huntington's Disease Degenerative neurological disorder

Chromosomal mutations

Karyotype reveals changes in -chromosome number and differences in structure In humans, only a few variations in number are typically seen Down syndrome, Turner syndrome, Klinefelter syndrome

Mendel's First Law

Law of segregation Each individual has two factors for each trait The factors segregate (separate) during the formation of the -gametes Each gamete contains only one factor from each pair of factors Fertilization gives each new individual two factors -for each trait

Membrane proteins

Many types Serve a variety of functions

XYY Syndrome

Previously called "supermale" syndrome Aggressive and more likely to become a criminal? Tall stature Learning difficulties

Meiosis

Reduction division Formation of -sperm and egg cells Gametes which are -haploid Shuffling of genes on homologous chromosomes to produce genetically different combinations A child receives one member of each homologous pair from each parent Homologous pairs may contain different versions of the same gene Alleles - alternate forms -a gene Both males and females have 23 pairs of chromosomes 22 pairs of -autosomes 1 pair of -sex chromosomes XX female or XY male

Inversion

Segment of a chromosome is turned 180° Reverse sequence of alleles Usually do not cause problems

Inheritance

These instructions are on chromosomes which contain units of information called genes

Abnormal sex chromosome number

Too few or too many X or Y chromosomes Y determines maleness SRY gene on -Y chromosome

Lysosomes

Vesicles that digest molecules or portions of the cell Digestive -enzymes

A missing piece of chromosome 5 may result in a child whose glottis and larynx do not develop properly resulting in an abnormal cry. This is called ________. a. Cri du chat syndrome b. Huntington syndrome c. Klinefelter syndrome d. Inv dup 15 syndrome e. Down syndrome

a. Cri du chat syndrome

Which of the following human syndromes is a monosomy? a. Turner syndrome b. Klinefelter syndrome c. Down syndrome d. Swyer syndrome

a. Turner syndrome

Which of the following is not a function of meiosis? a. cause an organism to grow b. create genetic variability c. reduce the chromosome number in gametes d. keep chromosome number constant from one generation to the next e. produce gametes

a. cause an organism to grow

A male is always homozygous for a trait that is _________. a. codominant b. X-linked c. autosomal d. dominant e. dihybrid

b. X-linked

The mode of inheritance for the pedigree show here is x-linked dominant. What are the possible phonotype(s) of the individuals marked with a "*"? a. XBXB b. XBXb c. XbXb d. XBXB or XBXb

b. XBXb

The filled-in squares of a Punnett square represent - a. the numbers of individuals with each version of a trait. b. all possible combinations of gametes based on a cross between the two parents. c. an exact ratio that must always occur when the same parents have 4 offspring. d. examples of some of the offspring that can arise from a one-trait cross. e. the gametes from one parent.

b. all possible combinations of gametes based on a cross between the two parents.

Some proteins can be viewed with - a. the human eye b. an electron microscope c. a light microscope d. a magnifying glass e. a dissecting microscope

b. an electron microscope

Endoplasmic reticulum

complicated system of -membranous channels physically continuous with outer membrane of nuclear envelope 2 type of Endoplasmic Reticulum Rough ER Studded with ribosomes Forms transport vesicles going to -Golgi apparatus Smooth ER Continuous with rough ER No ribosomes Function depends on cell Synthesis of -lipids detoxifies -drugs

An embryo produced by in vitro fertilization (IVF) may be tested for genetic disorders prior to implantation. How is this accomplished? a. Fetal cells are recovered from the mother's blood, and the DNA analyzed with a DNA microarray. b. Amniocentesis or chorionic villus sampling is performed, and a karyotype assembled. c. Blood is drawn from the embryo for genetic marker analysis d. A single cell is removed from a 6 to 8-celled embryo, and its DNA analyzed with a DNA microarray.

d. A single cell is removed from a 6 to 8-celled embryo, and its DNA analyzed with a DNA microarray.

Parents with the dominant phenotype cannot have offspring with the recessive phenotype a. True because the dominant gene must be passed down from each parent. b. True because at least one dominant gene will be passed down from each parent. c. False because one parent could carry the recessive allele. d. False because both parents could carry the recessive allele. e. True because both parents have the dominant allele.

d. False because both parents could carry the recessive allele.

Y carries SRY gene

determines maleness X is much larger and carries more genes X-linked - gene on X chromosome

Ultrasound -

helps evaluate fetal anatomy for -serious abnormalities Uses high-frequency -sound waves

Cells under the Microscope?

Are extremely -diverse Nearly all require a microscope to be seen Light microscope Invented in 17th century Limited by properties of Electron microscope Invented in 1930s Overcomes limitation by using beam

what is a cell and what does it do?

Cells - the basic unit of life Living things are composed of at least one cell -metabolize -reproduce -senses and respond to the environment

Testing fetal cells

Cells from amniocentesis or chorionic villus sampling Fetal cells can also be collected from mother's blood Amniocentesis Sample of -amniotic fluid taken Conducted 14-17th week of pregnancy Chorionic villus sampling Chorionic cells from where placenta will develop As early as 5th week of pregnancy

Duplication

Chromosome segment repeated Individual has more than 2 alleles for certain traits Inv dup 15 syndrome - inverted duplication of chromosome 15

Tay Sach's Disease

Disease caused by abnormal lysosomal enzymes Mutation in a single gene results in a malfunctioning lysosomal enzyme Lysosomes fill up with lipid (fatty substance) Normal until ~ 1year, brain deteriorates, fatal ~age 3

Principle of Dominance -

Dominant alleles are expressed over -recessive alleles Recessive alleles are masked by the presence of a -dominant allele

Recognition proteins

Enable our body to distinguish between our own cells and cells of -other organisms antigens

Counseling for Genetic Disorders

Even if no chromosomal abnormality is likely, amniocentesis might still be done to perform biochemical tests for over 400 different disorders caused by specific genes Testing for Genetic Disorders Testing for a protein Some disorders caused by a missing enzyme Test for quantity of enzyme produced Testing the DNA Genetic marker - relies on an abnormality in the DNA sequence due to presence of abnormal allele

Translocation

Exchange of chromosome segments 5% of Down syndrome cases caused by a translocation in previous generation between chromosome 21 and 14

Environment and the phenotype

Factors that can effect skin color Degree of oxygenation Sunlight exposure Jaundice

Sex-Linked Inheritance

Females are -XX All eggs contain an -X Males are -XY Sperm contain either an X or a Y These genes are only on the X Males have 1 alleles Females have 2 alleles

Genetic testing -

Fetal cells Children Adults

Golgi apparatus

Flattened sacs Receives vesicles from -ER Modifies -molecules Sorts and repackages for new destination -Some are lysosomes

Cilia and flagella

For movement of the cell or fluids past the cell Cilia shorter and more numerous than flagella

Channel Proteins

Form tunnel for -specific molecules Chloride ion Cystic Fibrosis most common serious genetic disease in the US A single gene mutation causes a cell membrane Cl- transport protein to malfunction Cells produce thick, sticky mucus that clogs the lungs 🡪infections

Sickle cell disease-

HbA = normal hemoglobin / HbS = sickle cell hemoglobin Mutation in the gene for -hemoglobin Red blood cells form a sickle shape when -O2 is low One small change in the Hb protein The sickled red blood cells cannot fit -through capillaries Symptoms - Causes joint pain, anemia

Incomplete dominance

Heterozygote has an intermediate phenotype Four-o'clock flowers Red+ white=pink Human wavy hair is intermediate between curly and straight hair

Genetic profiling

Individual's complete - Indicate the presence of mutant genes Indicates risk of developing common diseases Heart disease Parkinson's disease Diabetes Misuse of Information?

Autosomal recessive disorders

Infantile neuroaxonal dystrophy (NAD) Bedouin intermarriages All people have harmful recessive genes BUT the likelihood that you will mate with another person who has the same allele is low. Cohen Syndrome Amish Intermarriages The Amish make up only about 10 percent of the population in Geagua County in Ohio, but they're half of the special needs cases. Albinism Group of inherited disorders Little or no -melanin production

The Plasma Membrane

Marks boundary between -outside and inside of a cell Regulates passage in and out of a cell Structure of a cell membrane Phospholipid bilayer with embedded -proteins Polar heads of phospholipids face into watery medium Nonpolar tails face -each other Fluid mosaic model Proteins and cholesterol embedded into the -membrane Molecules may move and shift position Celiac Disease Ingestion of gluten wheat rye barley Immune system attacks lining of -the small intestine Lack of nutrient absorption malnutrition cramping diarrhea

Human life cycle

Meiosis reduces chromosomal number from diploid to haploid Gametes formed - sperm and egg Fertilization forms a diploid - zygote

Vacuoles

Membranous -sacs Larger than vesicles Rid a cell of excess water Digestion Storage

Hemophilia

Mutation in X-linked gene Lack of protein required for blood clotting Use this notation ONLY for X-linked genes XHXH = Normal female XhXh = hemophiliac female XHXh = carrier female XHY =normal male XhY = hemophiliac male

Why are cells so small?

Need surface area large enough for entry and exit of materials Surface-area-to-volume ratio

cytoskeleton

Network of interconnected protein filaments and tubules Extends from the nucleus to the plasma membrane Maintains -cell shape

Abnormal Chromosome Inheritance

Nondisjunction - can occur at 2 separate locations Meiosis I - when both members of a pair go into the same daughter cell Meiosis II when sister chromatids fail to separate Trisomy - 3 copies of a chromosome Monosomy - 1 copy of a chromosome

One Trait Inheritance

Original parents called P generation First-generation offspring -F1 generation Second-generation offspring -F2 generation Crossed violet flowered pea plants with white flowered pea plants All F1 are violet flowered

Punnett Square

Shows all possible combinations of egg and sperm offspring may inherit When F1 allowed to self-pollinate F2 were 3/4 tall and 1/4 short F1 had passed on shortness F1 had Mendel reasoned 3:1 ratio only possible if - F1 parents contained 2 separate copies of each heritable factor 1 dominant and 1 recessive Factors separate when gametes form and each gamete carries only -one copy of each factor

Pleiotropy

Single genes have more than one effect Marfan syndrome is due to production of abnormal connective tissue

Nucleus

Stores genetic material Organized into genes which specify production of proteins Nuclear envelope - double membrane -Nuclear pores permit passage -in and out

Polygenic inheritance

Trait is governed by 2 or more sets of alleles Each dominant allele has a quantitative effect on phenotype and effects are additive Result in continuous variation -bell-shaped curve Skin color is polygenic

Down Syndrome

Trisomy 21 Recognizable characteristics Short stature, eyelid fold, stubby fingers, mental disabilities Chance of a woman having a Down syndrome child increases rapidly with age, starting at about 40.

Mendel's experimental procedure

Used garden pea - Pisum sativa Easy to -cultivate Short -generation time Normally self-pollinates but can be cross-pollinated by hand Chose true-breeding varieties offspring were like the parent plants and each other Method Used Kept careful records of large number of experiments His understanding of mathematical laws of probability helped interpret results Particulate Theory of Inheritance Based on the existence of minute particles -(genes) Genes are physical units that are passed from parent to offspring

It would be possible for a male and a female to have exactly the same __________________ but they would have to differ in _____________________. a. diploid chromosomes; haploid chromosomes b. autosomes; sex chromosomes c. homologues; autosomes d. karyotype; sex chromosomes e. karyotype; autosomes

b. autosomes; sex chromosomes

A cow with black and white patches is produced from a white bull and a black cow. This is an example of - a. incomplete dominance. b. codominance. c. dominance/recessive trait. c. polygenic. d. pleiotropy.

b. codominance.

Chorionic villus sampling carries less risk of causing miscarriage than amniocentesis. a. True b. false

b. false

Which of the following structures would NOT be seen in a prokaryotic cell? a. cell membrane b. nucleus c. ribosomes d. flagella e. chromosomes

b. nucleus

Skin color is coded for by several different genes which results in a range of skin colors from very dark to very light. This is an example of ________________. a. a multifactorial trait b. polygenic inheritance c. pleiotropy d. codominance e. incomplete dominance

b. polygenic inheritance

The human life cycle consists of - a. adults who are haploid and produce diploid gametes, these gametes fuse to produce a haploid zygote which grows into an adult. b. zygotes who are haploid fuse to produce a diploid gamete which grows into an adult. c. gametes that are diploid and produce haploid zygotes, these grow into haploid adults. d. adults who are diploid and produce haploid gametes, these gametes fuse to produce a diploid zygote which grows into an adult. e. adults that are diploid who produce zygotes that are also diploid.

d. adults who are diploid and produce haploid gametes, these gametes fuse to produce a diploid zygote which grows into an adult.

A genetic profile includes - a. the location of all known genes in the human genome. b. the entire base sequence of an individual's genome. c. all of an individual's normal genes. d. an individual's complete genotype, including mutations. e. all of an individual's genetic markers.

d. an individual's complete genotype, including mutations.

Which of the following is NOT true with regard to the law of segregation? a. Each individual has 2 factors for each trait. b. Genes segregate during gamete formation. c. Gametes contain only 1 gene from each pair. d. During fertilization, each new individual obtains 2 genes for each trait. e. Each gamete contains 2 genes for each trait.

e. Each gamete contains 2 genes for each trait.

A tadpole that is undergoing metamophosis into a frog and losing the need for a tail would see abundant numbers of what organelle to help assist in the tail loss. a. smooth endoplasmic reticulum b. vacuoles c. centrioles d. microtubles e. lysosomes

e. lysosomes

Which of the following is an INCORRECT match? a. ribosomes - protein synthesis b. Golgi apparatus - protein alteration and packaging c. mitochondria - production of cellular ATP d. lysosomes - cellular digestion e. smooth endoplasmic reticulum - storage of water

e. smooth endoplasmic reticulum - storage of water

During meiosis, each pair of alleles on the homologous chromosomes sorts independently from all other pairs of alleles. This statement corresponds to a. the rule of multiplication. b. the law of segregation. c. the law of probability. d. gene theory. e. the law of independent assortment.

e. the law of independent assortment.

The possibility of Down syndrome increases as the mother's age increases because - a. her DNA is damaged through an accumulation of replication errors. b. her DNA stops checking for replication errors. c. fertilization no longer occurs correctly with older eggs. d. the contents of the egg contains the wrong signals for the correct development of the fetus. e. the possibility of nondisjunction increases.

e. the possibility of nondisjunction increases.

Phenotype

physical appearance of individual Mostly determined by genotype