4a Flashcards
somatic
germ
somatic-body cells, made up of body’s tissues and organs, DNA is not passed to offspring
germ- found in reproductive organs, develop into gametes, DNA can be passed to offspring
chromosomes in somatic cells
46
male gamete
female
sperm,egg
human gamete
23
homologous chromosomes
Have copies of the same genes/same length and general appearance
xy
male
xx
female
what nuclei has more genes
x
fusion of egg and sperm cells
fertilization
diploid2n haploidn
dip- 2 copies of each chromosome
hap- 1 copy of each chromosome
somatic is diploid or haploid
diploid
why is it important that gametes are haploid
when the sperm and egg fuse together the cell will have 46 chromosomes
what type of division do germ cells undergo in order to produce gametes
Mitosis
cells produced by mitosis
2 identical daughter cells
cells produced by meiosis
4
gametogenesis
production of the gametes
polar bodies
one of four cells produced by meiosis actually go on to become an egg/the egg will receive most of the organelles the other cells will become polar bodies
why is genetic variation good
produces variation in the offspring species can adapt to environments survival advantages a disease or change in environment is less likely to affect all of the individuals in a population
what happens when crossing over occurs during meiosis
exchange of chromosome segments between homologous chromosomes during prophase 1 of meiosis 1 this results in a new combination of genes
gene linkage
genes located close together tend to be inherited together
what must happen before able to reproduce
puberty
were are human egg cells produced
ovaries
what is the main female hormone that controls reproduction
estrogen
what happens to a human egg once it leaves an ovary
enters the fallopian tube
in what organ will a fertilized egg develop into a baby
uterus
were are human sperm produced
testicles
what is the main male hormone that controls reproduction
testosterone
what is the term for the cell that forms when an egg and sperm unite
zygote
fluid filled sac that protects a developing embryo
amniotic sac
placenta
connects the mother and the embryo/ allows exchange of oxygen, nutrients, and waste
how are the embryo and placenta connected
umbilica cord
pregnancy lasts
9 months
stages of pregnancy
trimester 1 2 3
Challenging for scientists to study DNA
DNA is a very large molecule far to small to see
cut up DNA into manageable sections
enzymes
restriction map
show the lengths of DNA fragments between restriction sites in a strand of DNA
polymerase chain reaction (PCR)
a technique that produces millions of copies of a specific DNA sequence in just a few hours
uses DNA fingerprinting
solving crimes/prove family relations/study biodiversity
clone
a genetically identical copy of a gene or an entire organism
bacteria that reproduce via binary fission clones of each other
bacteria produce identical genetic copies of themselves through binary fission
issues of cloning mammals
typically unhealthy
age quick
environmental factors cause genes to be expressed in different ways, controversial
why is genetic engineering possible
all organisms share the same basic nucleotides
recombinant DNA
DNA that contains genes from more than one organism
transgenic
one or more genes from another organism is inserted into its genome
issues with genetically modified plants
not a lot of research/ genes may cause allergic reactions/ negative impacts to the environment
genome
organisms genetic information
genomics
study of genomes
Human genome project
Mapped and sequenced all the DNA base pairs of human chromosomes/ identifies all genes within the sequence
genetic screening controversial
create tension within a family because of the results can reveal information about other family members in addition to the person who is tested
gene therapy
the replacement of a defective or missing gene or the addition of a new gene into a persons genome in order to treat a disease/ the goal is the add the gene to the correct cells and to get the gene to become part of the cells DNA
