Chapter 3 Flashcards
What is the first cell that we become?
Zygote
Heredity
Genetic transmission of characteristics from parents to children
How is the first cell created?
Sperm pushes through the membrane of the ovum; they fuse together to form a zygote
What are gametes?
The male and female reproductive/sex cells that form a new cell at conception/fertilization
Fertilization
Process where gametes join to form zygote
Zygote
New cell created via fertilization
What do gametes contain?
Genetic information that is transferred via chromosomes during fertilization
genes
basic biological units of genetic information and inheritance
what is the russian doll analogy of genetics
cell –> inside the nucleus is 23 pairs of chromosomes (except gametes) –> in these chromosomes are genes —> genes are segments of DNA
what do genes influence
physical characteristics and have the instructions for making proteins
What is DNA
the substance that genes are composed of that determines the function and nature of every cell in the body
what are genes arranged in
specific order and location along 46 chromosomes
chromosomes
rod shaped portions of DNA that have 23 matching pairs
TF: all pairs of chromosomes are the same
false; 23rd pair differs from its member of the pair and it determines the sex
how many chromosomes do the gametes have and how do parents contribute to the total number of chromosomes
23 chromosomes in nucleus of gametes; mother and father each contribute 23 chromosomes each to make the 46 chromosomes the zygote
what is mitosis
process of cell replication, ensuring every cell has same chromosomes as zygote
meiosis
process of cell division that creates gametes
Monozygotic twins aka
identical
monozygotic twins are created when
cluster of cells in the ovum split off after fertilization; creating 2 identical zygotes that were from 1 original zygote
monozygotic twin
twins that are genetically identical
what is responsible for differences between monozygotic twins
environmental factors
how are dizygotic twins created?
when two separate ova are fertilized by two separate sperm at roughly the same time
dizygotic twins are no more similar than
siblings born at different times
dizygotic twins aka
fraternal
variation between dizygotic twins is due to
env. or genetic factors
what increases the chances of multiple births
fertility drugs, older women, familial history, racial /ethnic/national differences (African Americans more likely)
mothers carrying multiple children run higher risk of
premature delivery and birth complications
23rd chromosome pair: girl vs boy
female: XX
male: XY
each gamete carries ___ chromosome from…
1 chromosome from each of parent’s 23 pairs
an ovum will contribute a ___; sperm will contribute a ___
ovum (xx): will always contribute an X
sperm (xy): will either contribute an X or a Y
what determines the gender of a child
sperm
what was the scientist’s name that experimented with pea plants?
gregor mendel
what is the dominant trait
the trait that is expressed, when two competing traits are present
dominant vs recessive (lowercase or uppercase)
dominant: uppercase
recessive: lowercase
recessive trait
the trait that is present, but not expressed when 2 competing traits are present
genotype
underlying combo of genetic material present (but not outwardly visible) - genetic info relating to both parents
ex). bb, Bb, BB
phenotype
the observable trait
genes vs alleles
genes: code for specific trait (which trait)
alleles: variation of a gene/ dif form (what form it takes)
ex.) coke vs cherry coke
where do alleles occur and what are they
occur at the same place on chromosomes
2 forms of the same gene - one inherited from each parenet
homozygous
inheriting similar genes for a given trait (BB, bb)
heterozygoous
inheriting different forms of gene for a given trait (Bb)
what is PKU
disorder; improper use of amino acid phenylamine
a single allele is a
pair of genes
PKU transmission and dominant/recessive trait
P: regular levels
p: carries recessive gene responsible for PKU
PP + PP: no chance of carriers (all PP)
Pp + PP: PP (50% of not carrying) Pp (50% of carrying)
Pp + Pp: PP, Pp (50% - carries) pp (25% - has PKU)
polygenic inheritance:
inheritance in which a combo of MULTIPLE gene pairs is responsible for the production of a particular trait
X linked genes
recessive genes that are ONLY located on the x chromosome
what kind of problems might arise because of the x linked genes
x-linked disorders – higher risk in males because they lack the second X
number of genes
25000
behavioral genetics
effects of heredity on behavior and psychological characteristics and personality
Down syndrome
Extra chromosome on the 21st pair - mental retardation
Fragile X syndrome
gene damaged on X chromosome - mental retardation
Sickle cell anemia
mostly common in African Americans
blood disorder - red blood cell shaped like sickles
poor appetite, stunted growth, swollen stomach, yellowish eyes
rarely live beyond childhood
Tay Sachs disease
death before school age, blindness and muscle degeneration, no treatment
klinefelter’s syndrome
extra X chromosome in males
underdeveloped genitals, extreme height, enlarged breasts
Environmental influences on disorders
sickle cell in Africa vs america
Genetic counseling
discipline that focuses on helping ppl deal with issues relating to inherited disorders
first trimester screen
blood test and ultrasound sonography
